Another way is to let surplus bees look after surplus comb. If you adopt the nuc method of making increase successfully you will have bees-a-plenty.
This fall I had a couple of production colonies that I did not allow to build up for wintering - I had harvested their honey - I let them sit on the combs until Nov 6th, and then I shook them out. There are no comb pests active up here at this time, and now I have 50 good brood combs sitting in my shed.
It is wise to plan to have spare brood combs in the spring. I have been moving away from overwintering double 10 frame deeps to overwintering 5 over 5 frame nucs, with a few 5 over 5 over 5 framers thrown in.
I will need those combs in the spring. I hope to sell a 1/3 or so of these, run 8-10 for honey, and then make increase with the rest. I bought no bees last year, not a single one.