plus you'd only be buying already produced gameplay/graphics...  you'd have to buy the company in order to achieve what you're thinking, I reckon.
if you're a recent lottery winner and you're looking for a  gamepark hobby business, may I suggest you  work out a deal with the guy who was doing the 3d racing engine...  rope in antiriad and 3 others for graphics, igive me a trial at SFX/soundtracks, and also take on pirotic as a commercial concern...  make guardian monsters a priority, but with gigas part of the contract too... hire artists (from the scene/thereabouts) for content, also sound artists for extra polish...
play your cards right with that, you might have 2 comercially releasable quality games, and a professional games editor...   call it $30/40,000  ?  6 months work...  8-10 people on the payroll...   
then there's distribution...  now this is a lottery win concern... I.E. not life and death...  how many GP32 owners are there that might buy from this site (not just...  say 5000...a guess......   charge 10$ per game. on a 32MB SMC (hoping you can find a cheap (2$) lot of 32MB SMCs...
voila!   business plan.  and you didn't need to buy an existing game to do it.  
what you reckon?