Upload & Sell: Off
It is true, part of the fun of alt image making, is finding great bargains, and resurrecting great old, forgotten gear. This gets forgotten sometimes.
To answer your question... Just My Opinions
1. If you are not sure if this is going to be your cup of tea, I would suggest getting a couple m42 screwmount adaptors ($12-$20) and explore the wonderful world of screwmount. Start with a 50mm, any of the Pentax/Takumar 50/1.4s are nice, and can be had cheap. KEH has several right now, all ~$100, I found mine on Craigs List mounted to an inoperable Spotmatic for $50. Coatings are the only major difference across the common 50/1.4s with the SMC versions being the latest. So in safe mode (ordering from KEH) 50/1.4 SMC $100, 28/2.0 ~$250, and a 105/4.0 ~$100, with adapters would put you within budget, and give you a taste. There are also countless screwmount lenses in other makes from most of the big names, just search ebay for m42. They are also the most likely "overlooked" type at a flea market or garage sale.
The other route to take would be starting with just one lens like a Contax Zeiss 50/1.7, it can be had for $200-$300 depending on condition, with an adapter would still be in range, but the road gets pricey from there going forward.
2. Right now, brand new GH2 bodies are going for ~$500, a pretty good value. Used, $450 and less. Used Canon 5D bodies are going for about the same, and while laking most of the contemporary features, have image quality that stands up still today. I realize at those prices you still need lenses, so you are probably going down the screwmount path to start.
Anyway, just my thoughts, you will get as many opinions as there are members here! The key is, have fun with it, don't get hung up on brands. Find a look you like and explore it. Find some cool bargains and brag here. Happy hunting.