Diversification is key, I break down to what I can afford to buy after paying off my bills, and put aside for saving plus other investments.
Its important to have 6 months of emergency cash, more the better, then I would see what I have left for shopping numismatic items, some months I have more money to invest into this hobby, but other months I would not even touch it. I would probably take up roll searching, since reading some of the posts in CRH, time consuming but maybe fun.