Depends on quit a few points. You want true older design or one with few modern touchs. Want motor back or like a lot of newer one with it lot farther out? Want it now or in year or two of build or more if broke like me.Going on 3 years and still not finished but getting close.
Cost wise probably buy used.Satisfaction of running a car you built is hard to beat.If you shop around you can find some very good buys in roller or turn key.End of season might be good time too.My dogs keep me going to vet like last two months and heck I might be giving mine away.
On my car I have built everything I can made likes of stuff I could buy,some cheaper in long run.Its taking forever,mostly money.Then again I doubt I would have gotten what I have if buying everything .Also doubt I would have saved up the money to have for buying turn key cat either. Plus I love fabrication and building as much as I can.IMO it will be ten time sweeter when I win the first race,figure might take 2 or 3 to get first win.After first one they seem easier.Plus win loose or draw its all on me.
Smart folks buy or have them built,determined folks build(not stuborn).IMHO do which ever gives you the most enjoyment thats what this is about right?