I bought a VFR bird, I flew the hell out of it. I performed minimal maintenance as required by annuals plus a new battery and IRAN starter. I flew it 880 hrs and sold it.
Every annual I have about 1000-1200 set aside for the annual and if it came in cheap then I would pick one or two accessories to IRAN. Within 3 years I had IRAN'd or replaced new: both mags, starter, alternator, carburetor, spark plugs and 3 of 4 cylinders. I had a friend give me free a brand new upholstery job for allowing him to use the plane one summer to get his PPL.
I held very firm to the rule buy what you want and live with it. Do not had fancy crap that you will not net 10 cents on the dollar for. If you do not like the plane as it sits then do no buy it. Buy the one you like.
I sold the plane for a very small depreciation after keeping it nearly 10 years and without putting a huge pot of money into.
When I wanted another plane I bought it with what I wanted on it, I made a very minor improvement to make it IFR capable (spent less than 5% of cost of plane) and fly it like I bought it. First three years I went through it the same way putting a Top overhead and IRAN accessories and new hoses and trust it to fly over mountains, night, and water....
I am deciding now if I am keeping this plane for the remainder of my aviation years or if I am going to get a twin. I might get a plane with auto pilot the next time around otherwise I am very happy.
At 175 knots on 15 gph it is not likely I would gain much more performance with a twin it would be only for personal growth of logging 500 multi engine hours or were I to get a CFI multi and ever want to train in it.
I once made a spread sheet of the actual costs of all the mods that I wanted on my bird some day and it came up to be $150k on a $69k bird and it is doubtful I could sell the plane for more than $80k with all the mods and total investment of $219,900. So I decided that performing mods is not the way to go.
Buy a plane, make it as safe as it can be and fly it. The plane will tell you what maintenance it needs.
On the other hand if your dad is a millionaire or you have stolen untaxed money that no one should ever know you had, then you can pour it into a big black hole called aviation upgrades, enjoy those fruits of your deed some what but have nothing to show for it when you sell it.
Or if you are a LasVegas Junkie trying ot kick the habit you can probably be better off moding your plane so long as you do not use it to get to vegas faster.
What was your first plane and what did you do with it? (Paint job, interior, avionics?). And post pictures!! Would love to see them and hear your story!