Hi pdxbmw,
If you are attracted to the idea of designing and building your own DIY mattress out of separate components and a separate cover then the first place I would start is by reading option 3 in post #15 here and the posts it links to (and option #1 and #2 as well) so that you have more realistic expectations and that you are comfortable with the learning curve, uncertainty, trial and error, or in some cases the higher costs that may be involved in the DIY process. While it can certainly be a rewarding project … the best approach to a DIY mattress is a “spirit of adventure” where what you learn and the satisfaction that comes from the process itself is more important than any cost savings you may realize (which may or may not happen).
If you decide to take on the challenge then I would either use the specs (if they are available) of a mattress that you have tested and confirmed is a good match for you in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) as a reference point or blueprint and try and “match” every layer and component in your reference mattress as closely as possible or use a “bottom up” approach (see post #2 here).
There is also more about primary or “deep” support and secondary or “surface” support and their relationship to firmness and pressure relief and the “roles” of different layers in a mattress in post #2 here and in post #4 here that may also be helpful in clarifying the difference between “support” and “pressure relief” and “feel” that may be useful as well.
The mattress shopping tutorial also includes a link to a list of the members here that sell mattresses online and many of them also sell latex and latex hybrid mattresses that use different types and blends of latex that have a wide range of different designs, options, features, return and exchange policies, and prices that that would also be well worth considering.
Post #3 here also includes a list of retailers or manufacturers that sell component latex mattresses as well and many of these are very similar to Savvy Rest mattresses. They are in much lower budget ranges than Savvy Rest and many of them have very good exchange/return policies as well which may be less risky than making your own mattress by buying individual layers and a cover that in many cases can’t be exchanged or returned.
There is also more information about wool toppers and how they compare to various foam toppers (at least in very general terms) in post #8 here and in posts #3 and #6 here and there are some additional comments about wool toppers and a list of some of the better sources I’m aware of (which I think you’ve already seen) in post #3 here but the only way to know how any combination of materials or components will feel for you will be based on your own careful testing or your personal experience.
Phoenix