You can get some home made ones from the modders on ECF pretty cheap
Boge Rev is cheap but not given good reviews (never tried one, so can't say)
Then you move up in price, you can get the mini vmod for just over 50 quid, the 18650 is a little more. - its not bad, but squonking is a pain when the bottle gets empty, but you sort of get the hang of that.
Rui over on UKV does the Du Bocage and his new metal feeder - Its a good BF, about 80 quid I think.
Red Sky Mods make cracking feeders, but you're looking at over 100 quid - Class feeders
Boggers box mods are good feeders and are a decent price if you just get standard wood, switch and cup - I can let you know tomorrow hopefully how good they are
Sweetvapes Grip Feeders - they have a unique...erm...grip shape
, I think they look fantastic, again, I can let you know in a few weeks how good they are
- massive waiting list on these.
Not many good feeders out there that are cheap btw