What is the opinion of Reddit about the
Microsoft Wireless Keyboard 800 (2VJ-00001)?

Are you set on a mechanical keyboard? If you want budget, then you probably don’t want mechanical. Good mech keyboards are very expensive. Excellent name-brand ones are usually in the $120-$200 range.

Assuming you don’t need mechanical:

Here is a list of well-rated wireless keyboards, sorted by price..

This Microsoft keyboard is basic. It’s got a good rating for the price.

This HP keyboard is $50 and is pretty popular. Even better ratings than the Microsoft one.