Hi packmanva,
Allassea is a trademark for Bernards which imports furniture and mattresses (most likely from China).
With any mattress you can assess the quality of the materials using the guidelines here and I would make sure that all the memory foam or polyfoam in the mattress were good quality materials for the budget range.
They have a CertiPur logo on their site but they aren’t listed on the CertiPUR list here * so I would also question them about their certification. I would also read post #6 here about foam mattresses that are shipped from Asia or China.
** Please check the newest CertiPUR list here)
I would also be very cautious about using reviews as part of any mattress choice (see post #13 here) because a mattress that works well for one person (or even many people) may be completely unsuitable for someone else to sleep on and the large majority of reviewers know little to nothing about the quality of the materials inside the mattress they purchase.
Outside of making sure a mattress is a good match for you in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences … the most important part of the value of a mattress purchase is the quality of the construction and materials inside it and it’s always important to make sure you know the type and quality of all the materials so you can identify any weak links in the mattress and make more meaningful comparisons with other mattresses.
Just in case you haven’t read it yet … the first place I would start your research is the tutorial post here which has all the basic information, steps, and guidelines that can help you make the best possible choices … and know how and why to avoid the worst ones.
Phoenix