Tank size would really depend on the specific species you intend to keep.
I would suggest a 75 gallon tank. I would plant it with plent of Anubias species of plants with some open swimming space. You may also mix in some low light tollerant stem plants like Hornwort or such. This would be optimum for 3 or 4 different specimens. You need to really decide on which species you want to keep and what tankmates you would include.
I wouldn't put much lighting on there, maybe a single bulb 4 foot shop light. They are cheap and readily available at any hardware store.
You will however need to spend you lighting savings on filtration. You would do well with a high capacity, slowflow canister, like an Eheim. Bichirs don't really like a lot of flow but need an extremly efficient filtration device. You may also consider a wet/dry filter with large surface areas (ex: bio balls, fishing line, etc.)
Bichirs are oportunistic picsovors (fish eaters) and will eat anything they can catch that will fit in their mouth. They also do well on a Carnivor sinking pellet and frozen foods like prawns and the ocasional chicken liver. They are very hardy and can be kept by most fishkeepers that have regular water changing regimen, and the desire to give them a healthy environment.
Good luck and Good fishing!