I have a BRS 5 stage and liked it... That is until I added the MaxCap DI system to it. I'd say go with the Spectrapure Max Cap from the start as it is a very good system. Also by what I understand, there is really no need for 2 carbon block filters so if you have the correct sediment and carbon block you can save money by replacing less filters...
if anything build your own and follow what they have in the maxcap 90gpd rodi unit. then added any little extra's you might want.. might save you money might cost a little less. but i highly recommend the maxcap or any of the spectrapure
To answer your question, yes there are better systems and for less money.
You would probably be just fine with the $120 Spectrapure unit here. MAXPURE MPDI SYSTEM
I own a MaxCap and love it but for many users one of their other systems is sufficient, especially if you have fairly good tap water and are just starting out in the hobby. There is no way you can build a similar system for less money.