If all you need is a cheap PCIe 2.0 HBA and performance isn't that big of a concern (i.e. you don't plan on using SSDs), go for LSI/Avago/Broadcom (or whatever they are called after the next acquisition...) 2008 based HBAs. They are widely available, well supported and battle-tested. If you plan on upgrading the platform soon (highly likely, given that the majority of PCIe 2.0 systems are already ~10 years old...) go for at least an LSI2308 based HBA - its basically the PCIe 3.0 variant of the 2008.
Main problem with the 2x08 controllers is performance - it is fast enough for HDD-only setups, but it quickly becomes a bottleneck when SSDs come into play.
So if you want to have a bit more headroom, go for a 3008 or 3200 based HBA - especially the 3008 aren't that much more expensive nowadays (and well within your budget), so I'd always opt for one of these if I have the choice.
For use with ZFS go for controllers with IT firmware - they are usually the cheapest variant anyways. Most controllers can be reflashed to that firmware though, so if you get a good deal on one with another firmware it's not a problem.
Controllers with the named chipsets are usually available as used parts by various brands (IBM, Dell, Fujitsu) and also as no-name parts from China. I don't have any experiences with the latter, but bought several used Dell and IBM ones for home/test servers. Never had any issues and all of them are still working fine, so especially for homelab/testing use I'd always prefer used enterprise HBAs over similar priced new consumer parts.
edit:
servethehome.com still has a list of HBAs for TrueNAS systems:
https://www.servethehome.com/buyers...s-freenas-nas-servers/top-picks-freenas-hbas/
Hasn't been updated in a while, but since you have asked for PCIe2.0, it's still viable...