Welcome G! Precancels are my favorite stamp collecting interest. The precancels.com website is a good source of info and contacts. I recommend joining a precancel society [in the US the PSS].
I find
ebay a better buying alternative to all of the other online auction sites by a factor of 50-to-1.
Right here at SCF is a good place to ask questions. Collecting by state is very popular.
What is your state? I collect AL, DE, MT, VT, and WA general [general in the precancel context means all cities all types all denominations].