You've got a Trimmer "Homeowner" which was a less expensive model than their "Original" model. Has belt drive off the engine rather than chain drive as their commercial models, and uses the belt as a clutch, rather than a single plate dry clutch. Other features were made less expensive to compete with McLane and King O'Lawn.

Based upon the picture, I'm guessing your machine is from the late 1980's. You can pin the date down by looking at the Briggs model numbers on the starter shroud next to the carburetor. The numbers will look something like 80201 XXXX-XX 8806XXXX. The first four digits of the third set are the month and year of manufacture, i.e. June 1988 in this example.

While the Trimmer Homeowner is a pretty good machine for non-commercial use, your price is too high for a 25 year old mower. If you're willing to negotiate, you might be able to sell it.