Hi alohabob,
The first comment I would suggest is to exclude FBM as a reasonable option for a mattress unless it made no difference what types of material you were purchasing and that their description didn’t match what you will likely receive. There are more comments about them in post #2 here and post #2 here and a search on FBM will also bring up many more. I would not do business with them until they could give some reasonable assurance that what their customers think they are ordering is what they will actually receive or unless “random foam” was OK in the mattress you were building.
There’s really not much point in taking any time to analyze the layering if the materials are coming from them since there’s no way to know what you will receive.
Ideal quilting is a wholesale outlet only and only sells to manufacturers. The SleepEz cover is very good quality and value … particularly if there is latex in your mattress (which needs to be well protected from ultraviolet and ozone). You can see some pictures of it in post #33 here (the actual cover is off white and not the color that the lighting in the picture gives it).
There are also some good options in the foundation thread here which would be a similar price (the wire grid frames) to what you are looking at making and would have the advantage of being a little higher, providing better ventilation, can also be used for storage under the bed.
Out of the options you are looking at … the Ironman would certainly be my choice. They use good quality materials and at the prices you are mentioning (you don’t mention the size but I would assume it is at least queen size) they would be good value. Some of my thoughts about them are here.
You’ve probably seen this as well but some of the better options in the Hawaii area (at least Honolulu) are in post #2 here and the posts it links to.
Hope this helps.
Phoenix