I set up a small spreadsheet of vendors, feeders, prices, shipping, etc.
I only order 4X per year, so at order time, I quickly go through the list, as prices & availability can change, depending on supply & other factors (it's a competitive business).
You can do a general search, like
reptile feeders
or get more specific, like
dubia roaches, etc.
You
can save more at places that offer free or flate-rate shipping, and by ordering multiple types of feeders (e.g. dubias, silkworms, superworms) in the same order. This is where the spreadsheet helps; one vendor may have a better deal on roaches, but higher for silkworms, etc. and you have to consider the whole order.
Quality & service can mean a lot too. If there
is a problem, notify the vendor immediately. Anyone can make a mistake, and the best vendors will remedy it ASAP because they'll value your custom.
OTOH, some vendors just do better than others on some things, e.g. Symton specializes in BSFL.
Others are better with Dubias, or Silkworms, etc.
Geography can make a difference right now (COVID). All the shippers (FedEx, UPS, USPS) are experiencing delays, so choosing a vendor geographically close(r) to you can make a difference of several days.