reply to u/Impossible-Dance7442 at tk
Looks like a portable 4 bank B model Underwood from 1926 (see also: https://typewriterdatabase.com/underwood.4.typewriter-serial-number-database).
Appears to be in reasonable cosmetic condition with good decals, but the internal condition is going to be the biggest determinant of value. In unknown condition they sell regularly for $20-50 in online auctions, but cleaned, oiled, and adjusted from a professional repair shop they might go as high as $400, or perhaps $550 if you've had the rubber on the platen re-covered. Thinking that fair market for this in even the most pristine condition is $800 is pure folly unless it was used by someone famous. (The lack of interest from antique shops is a solid indicator here.) It assuredly is not going to make you rich, unless you bought the house from a famous author.
You might find some useful advice from some of the articles at: https://boffosocko.com/research/typewriter-collection/#Typewriter%20Market They're written with first time buyers in mind, but you could also view them from the first time seller perspective.
A local repair shop might give you a few bones for it and give it a new life: https://site.xavier.edu/polt/typewriters/tw-repair.html
You could also donate it to a local thrift shop.
Your best bet for time and money invested though, is to gift it to a kid or teenager you know who's interested in writing, perhaps as a birthday present along with a copy of either: (1) Polt, R. The Typewriter Revolution: A Typist’s Companion for the 21st Century, 1st ed.; Countryman Press: Woodstock, VT, 2015. (2) Flint, W. D. The Distraction-Free First Draft; One Idea Press, 2023.
Good luck with it.
Alternate version of this with heirloom push is also at: https://www.reddit.com/r/typewriters/comments/1mbf185/comment/n5mdydi/