I bought a 450 in 1984, about a month before they went Customer Direct. That cost me about $100+/-, people ask if I was mad? I explained that the price I paid was a good deal, and they were silly/foolish if they didn't buy one customer direct! (They were the cost of a used S&W back then, and similar now too!)
It took my best friend about 10 years to buy a used 450. After he was up and running, he admitted I was right. (An admitting like that is very rare indeed!)
I've upgraded all along, so I've been at the "B" grade for many years now.
A recommendation: ASAP, buy all the shell plates you think you will need! The price just keeps going up, From about $6 in 1984 including locater buttons. The case mouth powder funnels were (and can still be) separate. I had to buy a 357 Sig/40 S&W 10mm plate last spring and wow!
If you look at the chart/list that tells which plate for which cartridge, you will see that there are multiple cartridges per plate. At that point all you need is the powder funnel. So 45ACP, 308, 30-06, 7 & 8 Mauser, 270 Win and 280 Rem and 284 Win, and a dozen others all use plate #1! Some of the funnels share more than one cartridge too. 308/307, 30-06, 30-30, 303 British, 34-40US, and 7.62x54R all use funnel #8. I have about 15 shell plates and 19 powder funnels and progressive load around 95 cartridges on my 550B! (I load 117 total)
I have about 10 tool heads. I always keep 1 or 2 empty for a hurry up situation, and keep set up the following: 38 special, 357 mag, 9mm, 357 Sig 44 Special, 45 ACP, and 45 Colt (I need to strip down the 44-40, as I sold the guns.) You'll want a powder thru die for each tool head! I keep a powder measure on 45 ACP and 45 Colt and have 2 that get shared with the rest.
HINT: put a tag on your measurer with the powder and charge. Post-it notes need a rubber band or tape in addition to the adhesive! Too many powders look the exact same!
Enjoy your loading.
Ivan