Are you 
collecting cards or are you 
investing in cards?  
As a 
collector, I'd try to fill in some items from my want list.  
As an 
investor with only $450 to play with (which is really peanuts in the grand scheme of collecting economics) I would focus on nice cards of major HOFers.  Personally, I think there is great value in some of the early 1970s Topps issues.  There are high #'s, condition sensitive sets, and a ready market.  In terms of whether to buy one card or several, I have always preferred to get ten 7's instead of one 9.  I just think of it as diversifying.  Plus it looks a lot better spread out on the desk.