Yet another investment question...

[StevieV]

Hi all. I'm thinking about getting into one particular vintage card, partially because I like it but more so because I see potential in it to go up in value. I'd rather not say what card it is but it sells for about $500 in a PSA 8 and $250 in a 7. 8's have a population of about 80 and 7's about 100. Would it be wiser to buy one 8 or two 7's for my $500? I've been wondering about that for a while now. If you're looking to invest and you can buy two PSA 7's for almost the same exact price one PSA 8, which would you prefer? Interested in opinions. Thanks.