I think all you gain is lumbar support from the regular seat. Buy an add on support for $5 at a dollar store? My 6 way tilts front or back a bit, lumbar support is adjustable and the back can be reclined if you are crazy enough to turn the knob for about 5 minutes, none are real important.
Seats are incredibly expensive. It's never financially feasible to buy parts from a dealer to change your seat. I'd start looking at junk yards, or RV converters who have pulled the OEM seats out to replace with their own.
I have the basic seats, they have the 2 levers on the side to adjust fore and aft angle of the seat. No lumbar, no heated seat and just driver arm rest.
Searching the internet for the parts and pieces can sometimes yield a cheaper alternative. I put in aftermarket heated seats, cost was $60 for both seats, with back and butt warmers. While it was inexpensive, the labor (my time) could be argued at costing more than the original option. My first heated seat took my cousin and I about 3.5hours of doing and learning. The second seat took just myself about 1.5 hours.
You can buy better lumbar supports that have airbags and they are fairly inexpensive on Amazon. But again, learning how to re-upholster your seat and remove it from your van will take some time.