I would not suggest using FL for sampling. I used it for a long time for that purpose and found it limiting, especially once I started using Ableton Live. Live is much more intuitive in terms of sampling, does a lot of stuff to save time as opposed to FL, and in general I prefer it for a lot of other reasons too.
As for records, like everyone else said get 'em anywhere you can. Thrift shops, record stores, peoples basements, etc. Some of the best records I've found for sampling from are ones I grabbed for $3 cause they had a cool name.