Amazon offers the Comp Cams Zex Nitrous Oxide System for $112.48 $112.75 with free shipping. That's the lowest price we could find by $202. ZEX dry nitrous systems feature an "Active Fuel Control" that reads bottle pressure and adjusts fuel enrichment to purportedly provide optimum power safely at all bottle pressures.

Note that although this item is currently sold out, it can still be purchased at this price for delivery when available.