APMEX has some fairly reasonably priced items, but their reputation is definitely NOT for being low-priced. Their shipping time frames are pretty standard
and long delays aren't common with them. There will be the (+/-) 7-day delay if you pay by check/bank check/USPS MO, but if you pay by credit card
(subject to 3% price surcharge), their shipping time is about as good as you can expect.
The advice to fully read all vendor website info about payment terms, processing time frames and shipping time frames is good advice. In addition to that,
also call their 800 tel# and go over all your questions with vendor phone reps. They're usually very helpful.
If I had to make one generalization though, my experience has been that the really low-ball prices generally do come coupled with longer shipping delays.