There are some advantages to buying a used bullseye pistol.
The biggie is money: a used wad gun will sell for half to three quarters of what a comparable new gun will. And the used pistol might come with accessories such as a dot sight, grips and magazines that wouldn't be included with a new gun. So, altogether that can mean a savings of several hundred dollars.
Another advantage is time: even a so-so used pistol will do you more good today than a custom wonder pistol that won't be ready for another nine months. And a new pistol generally needs a week or two to be broken in before it's match ready.
Almost all bullseye shooters wind up with more than one .45. So, if you're just starting out, I think it might be worthwhile to get a good used gun now to shoot with this summer. After you've gotten some experience, you'll have a better idea of what you want so when you do order a shiny new custom wad gun, you'll get something you can be happy with for a while. Otherwise, the dream gun you buy today might not fit your tastes in a few months and you'll wind up spending more time and money having additional work done on it.
When I started in bullseye, my first .45 was a plain Springfield Armory 1911A1. I hadn't bought it as a bullseye gun but I had it and I wanted to try bullseye so I used it. It didn't group better than 5" at 50 yards but that was good enough for the Marksman class (where most people don't shoot well with the .45 anyway!).
Later that summer, I bought a used Essex/Colt wad gun from a friend who was "upgrading" to something else. It wasn't pretty and it had seen a lot of use but it still shot well. I had a lot of good luck with that pistol and it took me into the Expert class.
After a couple of years, the Essex/Colt began to have some extraction and ejection problems. I didn't have much luck getting it fixed and the alibis were definitely holding me back. So, when I had a minor financial windfall, I bought a new Rock River Arms pistol and I've had great luck with it ever since. But I still have a couple of other pistols that I keep as backups or loaners, too.
I would have advanced faster if I'd gotten the RRA gun sooner, but I have no regrets about buying the Essex/Colt. When I get the extraction problem fixed I plan to sell it to another up-and-coming shooter and I expect it will give him good service as well.