I agree with everyone you can make a lot of toys yourself especially whips, paddles, crops and canes cheaper and better suited to you than you can buy them. Furniture too is always cheaper to build.
On the subject of buying toys I recommend shopping around hardware stores, sewing stores, farm and ranch supply's, pet stores, even dollar stores have great items you can easily re-purpose.
If however your looking for something that you won't find in the vanilla world or can't make here's your best bet for online stores in MHO:
SubShop- Lightning and daily deals if you keep an eye out you can get some really good stuff for a really good price, gags, arm binders, harnesses and such. Mainly it will be leather or leatherette gear not much in the way of insertables and whips.
Extreme Restraints- Dildos, Butt plugs, and Anal beads, oh my! This is your go to place for good quality and good selection of insertables. This is also where you wanna get any of the whips, floggers, canes, and paddles you can't make or buy. They have good quality and decent selection. you can get your leather gear here as well if you like but I would advise against it. The quality is good but nothing to write home about and its a little on the expensive side because a lot is brand name (Strict Leather).
JT's Stockroom- Welcome to the land of weird and wonderful, and expensive. This site is over priced on damb near everything, BUT the redeeming factor? Cool toys and gear that's hard to find elsewhere. Trust me some of the toys are worth it.
In terms of fetish and slut wear I recommend Honor Fetish clothing and ODGirl, which is actually a site that caters to club dancers and strippers.
Hope this helps man.

Masters never complain about the cost. Best you get some lessons to make sure you don't kill her.

I like Tractor Supply.  That is where I get most of my punishment toys.  Good cuffs can be acquired from Ebay.  As far as gags I don't like them.  Almost anything else can be made yourself.  If you get really serious about turning that basement into a proper dungeon, most designs can be acquired online.  You should try it.  Take a little time and practice invest in the right tools.  It can be fun.

you can find alot of whipping and spanking tools right in your back yard, i know your asking for whips, how ever take it back to when you were a child, i know when i did something wrong i had to pick my whipping tool i alway had to get a switch thin tree branch the belt or his hand i asked for his hand, i know from spanking "b" my hand gets sore, so i do the same thing i have found that a cable cord works great three swats she in pain, or go to a sports store and buy i pingpong paddle they work great also, or just take old belts you dont use cut them into strips wrap the base and there you go. the only big ticket item i have bought "b" her collars, any how happy shopping, even goodwills sometimes have items, i feel if "b" asks for a tool she  has to earn the money for it this way she might resepct the item more.

my Master gets all of our iteams through JT stockroom

Could anyone tell me which is the best (and cheapest) online store to buy bdsm equipment and tools?

...

I would suggest for a good riding crop, rather than pay the inflated prices most of the BDSM Stores tend to charge, go to a good saddlers and choose a crop from there, you will find it's half the price and usually twice the quality. Also you can get exactly the type and design etc that you are looking for or have in mind.

I agree with PeJay. Good leather crops and whips can be had at a tack shop, usually with a good selection and price range, as opposed to something seen on the 'net. A good leather crop is the first tool to buy, and I can't stress too highly the value of actually trying it in hand when you're new.

Later, you will develop the ability to judge things online by having come to know value in reality.

Yes, I LOVE old hardware stores; your imagination can run wild with what you will see.

Alan

I like JT's Stockroom as well, a little pricey, but their quality is outstanding in my experience

well as with most things you should shop around most store will have a few decent quality items for a really good price but then the rest of their stock won't be at such a good price or such a good quality. I will admit though that if your looking for high quality gear Extreme Restraints does have a pretty good selection and most of their prices aren't too astronomical.

One thing you could look at as well is building what you can yourself its satisfying and it gives you the option to make what you need to put your ideas into practice.

Could anyone tell me which is the best (and cheapest) online store to buy bdsm equipment and tools?

I'm just in the beginning of training my slave and need a good whip for her!

I looked at this one, but are not sure about the price:

http://www.1-class-erotik.dk/product.asp?product=5135

 

I would suggest for a good riding crop, rather than pay the inflated prices most of the BDSM Stores tend to charge, go to a good saddlers and choose a crop from there, you will find it's half the price and usually twice the quality. Also you can get exactly the type and design etc that you are looking for or have in mind. As for real whips I have found these people very good and their prices aren't bad either,

http://www.murphywhips.com/MW02E010SnakeWhip.html

good luck and I hope you find what you are looking for. Incedentally you can also look in hardware stores and builder's merchants etc and let your imagination fly, for some very interesting "toys" and equipment at low prices lol