This site is frequented by mostly audiophiles. I don’t think I’ve ever read a post where people didn’t extoll the virtues of higher priced equipment, well beyond the OP’s budget.
Component synergy is key (i.e. matching components that compliment one another). You are not going to hear an appreciable difference by adding a $10,000 preamp to an $800 system because the rest of your system isn’t capable of resolving the details. That isn’t to say that an $800 system can’t give you an enjoyable musical experience.
You’ve been given lots of examples of preamps that fit your budget. The reality is that until you actually hook one up, you won’t know how it sounds in your system.
There are a lot of deals to be had in the used market. Audiophiles tend to always be upgrading their components (in their pursuit of audio nirvana). Keep your eyes open for deals that fit your budget.
And don’t forget to enjoy the music!