Congratulations on getting into trikes.
You're budget may be a bit low and that's going to be the hardest part to work around. Everything is expensive now. Just new tires will eat half of your current budget. In the end, things cost what they do. Sometimes waiting for the best deals can take years to score and long term projects are much more likely never be completed, which is time and money spent but never rewarded. A budget is good to have, but so is a finish date, which many never set on a home project. A budget will keep the project from running away a completion date will help keep motivation up.
The biggest thing to check on the 110 is the frame. If there are cracks, have them welded up now, before they get worse. The engine is a stressed member, it's integral to frame stiffness. Make certain all engine bolts are there and tight or it puts more stress on the frame. There's a bolt/spacer or two that go through the rear of the frame, both sides. Make certain those are there and tight as well. I think one of them goes through the stock muffler as a mount, which is why the bolt is often lost when the exhaust is removed in the middle of a project and never reassembled.
Hopefully it has all metric fasteners still and someone hasn't ed in some SAE. That's almost guaranteed for the recoil starter bolts. I think, by law, at least one recoil bolt has to be some random SAE, probably from a junked Murray mower that's sitting in front of the trailer house, next to the filthy Escalade with a flat tire and one cellophane window. If there's bolt or nut with red paint, that means danger. If it's tight, leave it alone. If it's loose, the hole is now twice the stock size and you'll need at least a 1/2" NPT, preferably from the derelict plumbing of a dilapidated house. I'm pretty sure I've seen that episode on YouTube, maybe the FTWH (FixingThingsWithHammers) channel.
Good Luck
The story of three wheels and a man...