1897 O is the one to look for in the higher grades. 20 bucks is OK for any of 'em. 97, 97O, or 97S.
The mintmark is on the back, under the wreath.
Even if its not, 20 bucks is still OK. the 97 and the 97S might retail for as low as 15, but what's it matter? 5 bucks? This is not an investment coin anyways, so if ya want it, go for it.