My cast bullets, that I don't cast myself, come from mastercastbullets.com and Missouri Bullets (with master cast being my first choice) and I have never had a long wait. Both have always supplied bullets in a very timely manner and the prices are very good and the bullets are very accurate. Everyone has a company they personally like, but the cast bullet field is very competitive and all must make good bullets or they will be out of business very quickly.
This may come off as "back patting," but I wonder how many have actually taken the lessons over the past six years to heart:
It seems obvious to me, but with all the hue-and-cry about component availability since O was first elected, the critical thing that most should have learned from all this is NOT to wait to place an order but to be sure that your stock is kept up so these problems don't stop you. If you always maintain at least 6 months of stock, then a 6 month wait is not a critical problem. Anyone, IMHO, who has a favorite bullet and does not order in case lots is simply asking to be out of bullets at a critical time. This is particularly true for jacketed bullets, where a case lot is as cheap or cheaper than the plated bullets (that I have NEVER found to be acceptably accurate for me). Buying 500 or less to try is smart, but once you find a bullet, order a LOT. This also goes for primers and powder--be sure that your favorites are well stocked in your loading room. Plan ahead and save to make the large purchases.
About eight years ago, I noticed that I could buy Montana Gold 124gn 9mm JHPs in case lots for only a penny or two more than I could order cast lead bullets, so I began to stock up on jacketed bullets from MG, Zero, and Precision Delta. All during the shortage, I have maintained my stocks by placing orders and waiting, with enough bullets to last through even twice the estimated shipping time. My only "problem" is the price has again gotten to the point where I will have to begin stocking cast bullets as the price difference has grown too large again.