#1
I'm interested in having a play about with one, and my band are interested in doing some Bon Jovi covers atm, so I thought this would be a good excuse to buy one

Looking to buy cheap but reliable

Any suggestions, or things to avoid?
I've no clue when it comes to talkboxes.
A quick google search showed me a Danelectro Free Speech?
LesPaul
Pedals
OrangeRocker30
My band
PBT Native: Resident Graphics Monkey

#2
make your own one.
i did for my a level tech project, didnt get a great mark because i had to sacrafice the sound for the look and practicality of the unit, but it works.
cheap to make too.
just by a compression driver speaker and a funnel. there are loads of great vids on youtube of how to make your own