RNM

I just got a used Sovereign Model II - looks like it is from 2004 - and am trying to acquire the correct breaker sub panel without spending $570 (see https://www.hottubspasupplies.com/catalog/product/view/id/36184/s/301757-breaker-subpanel-box-1/category/2/). I am no electrician - we're hiring one to install this - and am trying to find the right setup.

Can I get any breaker box that will hold a 30 amp and 20 amp breaker? Any thoughts on how I could find the right set up and save $$?