Yes, Riverbank Armory AKA m1carbineparts.com and No Guts No Glory on Gunbroker.com AKA abcleigh on Ebay is the notorious California seller referred to in this and other forums.

You have four choices. If you are on a budget or impatient, get reproduction parts at reproduction parts prices so you have kinda what you want while you save up money, learn how to spot fakes (Humped or what? - Military Surplus Collectors Forums), and search for real parts.

Or, don't buy the reproduction parts and just use what you have while you do the same things mentioned above.

Or, you could re-evaluate whether you really need to "correct" or "restore" your carbine in the first place. M1icon carbines had early features for maybe the first 4-5 years of their service. The vast majority were rebuilt and upgraded after World War II, and then they were used in their improved rebuilt configuration (Type 3 band, flip safety, adjustable rear sight, etc.) for many years after World War II, in Korea and elsewhere Does anybody else like late model features? - Military Surplus Collectors Forums

Even if you find a genuine Type 1 band, flip site, etc. you still won't have an original carbine. It just isn't the same thing. You could end up spending a lot of money on something that is worth less than the sum of its parts.

Finally, if only an early feature World War II configuration will do, you could save up $1000-2000 and buy the real thing. Original configuration carbines are out there, they just aren't cheap.