Hi everyone, I was hoping to get some suggestion about any particular foot controller that can be used by a drummer to play backing tracks on Ableton Live. It needs to be small enough to fit with the rest of a drumkit so easy to reach, also not super expensive... Any idea?

Line6 FBV series, Eowave, IK Stealthpedal are all small or somewhat small. They all need a computer w/USB and send CC's which could trigger clips.

how many feet do you have?

Wouldn't it be more sensible to trigger via a roland octopad?

Yes it would be pretty easy... Have you got £400 that I can borrow?

How many switches do you want?

I ask, because I've made my own USB/MIDI foot switches from USB computer mice, keyboards, and joysticks.
I've also made (non USB) MIDI foot switches from broken MIDI keyboard controllers, and I made a CV (Control Voltage) foot switch from an old drum pad/trigger.
As you may be able to tell: I like foot switches.

They're not hard to make (relatively speaking) ***once you find:
- the switch(es)/button(s)
- a bit of wire
- something to strip the wire ends - an Exacto knife or even a pair of scissors can work
- a soldering gun
- solder
- a nice/strong shallow container to attach the switch(es)/button(s) to, and hold the guts of whatever USB device you're using.

AND provided you have:
- some USB or MIDI device to make it out of
- a screwdriver to take the USB or MIDI device apart (you can always try BREAKING it apart, but I don't recommend it - been there)
- a drill to make a hole in the container for a switch/button
- and software that enables you to do what you want to do with the hacked device.

*** USB peripherals (e.g. computer mice, keyboards, joysticks, steering wheels, acceleration/break pedals, flight simulator stuff, drawing tablets, track pads) can all be used to send MIDI data to your music/audio software (provided it accepts MIDI as a control source - which Ableton Live surely does).
There is a variety of software (some free) for both Windows and Mac OSX that will recognize your USB (actually HID - Human Interface Device) peripheral(s) and send the information coming from it/them to your music/sound software (Ableton Live in this case) as customizable MIDI messages.
I use Bidule for this, but there are other options I can point you to if you're interested.

I've hacked a descent foot switch together in about 20 minutes. Maybe less, but I've made quite a few and got faster at it..
Really, the only thing that can be a bit fiddly is the soldering.
My recommendation if you're new to soldering (and if you bother to go down this road to hacked foot switch paradise), is; if you go to an electronics parts shop, and you can afford it (I think they cost around $10 where I go); buy a little stand with clamps on little moveable arms [and an attached magnifying glass] to hold the wires still while you try to solder them.
ALSO: a soldering tip: heat up the wire and coat it with solder first - don't try to drop/dab solder onto a bare wire while you hold it against whatever you want to connect it to. Things will go A LOT smoother if the end of the wire is already coated (because then all you have to do is heat up the wire tip/end while it's touching whatever you want to connect it to.

OK, I'll shut up. You didn't ask for an electronics lesson.
I certainly don't expect you'll go this route,
but there's some info if you need it.
If you're keen to try to build your own foot switch this way let me know - I'd be happy to provide further info on whatever I've discovered along the way.

Here's a video clip of me using some of my home made foot switches while playing piano (to a somewhat abrasive sonic effect, but that's partially because I didn't really practice before making the video recording - nothing to do with the foot switches. It gets better around the 2:00 mark in my opinion. The switches worked great though).
These (four switches) were made from a single Logitech joystick I bought at a thrift store for $4.

http://www.youtube.com/watch?v=bTwl69_279c

There are many (countless?) tricks/methods you can employ to enable, for example, just two switches to trigger many different tracks/samples/recordings. One way is to have one switch cycle through a bank of tracks/samples/recordings and have the other one trigger them. Another option is you could have the tracks/samples/recordings automatically play as you cycle through them with one switch and have the other switch either tell the music/sound software to repeat/retrigger the current track/sample/recording, mute it, reverse the cycle order, change the cycle selection, or restart the cycle from a set beginning. These methods can also work well with patterns.

The above video is a recording of me using a contact mic to trigger samples while I control a buffer effect (on the samples) with foot switches. WHICH REMINDS ME of another option you can employ - using contact mics on your drums to trigger Ableton Live tracks that are selected/readied using foot switches.

Anywhooo,

best of luck with whatever you do or find.