It would be helpful for me (to help you) and for others if you could share a few clear pics of your Hauserman pool table.
Without seeing your pool table, I can only give you general information.
Hauserman, Inc. was the parent company, and they primarily focused on sales of office and school furniture under their "Educators" brand. They sold things like library shelving, school chairs, desks, cabinets, etc.
They sold pool tables under the names "Hauserman", "Rainier", and "Cascade". They were sold through independent distributors and big-box retailers like Simpsons-Sears, LTD.
The pool tables are residential-grade furniture-style pool tables. They did have a full one-piece slate as you mentioned. I would consider them a middle-of-the-road residential-grade pool table from that era. They aren't worth much now because of their outdated style and because the market is currently flooded with high-quality used pool tables. Worth a few hundred dollars in general, depending on condition.
Here are a few Hauserman pool table ads (from their retailers) from 1976 and 1977:
1977 Hauserman Pool Table Ad
This was just part of a 3/4-page Simpsons-Sears newspaper ad in a December 1977. Funny thing is that the price on this was about 35% higher than the Brunswick Briarwood pool table (which was shown in the same Simpsons-Sears ad.
1976 A&P Distributors Ad
This ad mentions that A&P Distributors are an authorized distributor for Hauserman pool tables and accessories.
Here was a Hauserman pool table that was for sale in 2017, and sold for $400: