Hi alchemista,
Welcome to the Mattress Forum! :).
The best place to start your research to make mattress shopping less confusing is the mattress shopping tutorial here which includes all the basic information, steps, and guidelines that you will need to make the best possible choice … and perhaps more importantly know how and why to avoid the worst ones.
Two of the most important links in the tutorial that I would especially make sure you’ve read are post #2 here which has more about the different ways to choose a suitable mattress (either locally or online) that is the best “match” for you in terms of “comfort”, firmness, and PPP that can help you assess and minimize the risks of making a choice that doesn’t turn out as well as you hoped for and post #13 here which has more about the most important parts of the “value” of a mattress purchase which can help you make more meaningful quality/value comparisons between mattresses in terms of suitability (how well you will sleep), durability (how long you will sleep well), and the overall value of a mattress compared to your other finalists based on all the parts of your personal value equation that are most important to you.
A few of the manufacturers that are members of this site have a discount code which are listed in the membership list here but for most of them you just need to let them know you are a member of the forum when you make your purchase and there isn’t a specific code.
Phoenix