Hi booroo,
Just in case you haven’t read it yet … the first place I would start is the tutorial post here which has all the basic information, steps, and guidelines you will need to make the best possible choices … and know how and why to avoid the worst ones.
Post #2 here includes a list of the better options and possibilities I’m aware of in the Austin and San Antonio areas.
Restonic is a national brand that is made by different privately owned licensee factories across the country (see this article that lists the largest 15 manufacturers) and in some cases can have some good quality/value but outside of careful and objective testing for PPP (Posture and alignment, Pressure relief, and Personal preferences) using the testing guidelines in the tutorial post … a mattress is only as good as its construction and the quality of the materials inside it … regardless of the name of the manufacturer that makes it (see this article).
Phoenix