I know I'm a greeny just need a little advise. So there this 1909 Lincoln wheat penny no mint mark full rd looks like PR but PR's are usually S mint mark for $88. Is it worth it?
Proofs are specially made coins and differ from business strikes. Although there are some very fine looking business strikes, they can never be proofs (as different die sets are produced to make either business struck coins or proof coins). The San Francisco mint has produced both proof and business struck coins over the years, so having a mintmark is not an indicator of which strike a coin is. Just where it was minted. Smaller mints seem to be the sources for proof coins...at least it seems that way lately. For $88, it sounds like a price associated with a decent grade 1909 specimen. But probably not a proof. Without looking at that specimen, it's hard to say if it's a good price or not.