I frequently scan the Craigslist ads in the N. Florida area and I seem to remember seeing someone selling a boom for the H22 recently, but for the life of me I can't find it now. However, there is someone selling a Hunter 22 project boat complete with trailer for an asking price of $1500 in Gainesville, which might be an alternative worth looking into for parts. Probably not too much more than what a new boom would cost and you might get some other stuff you need in the deal.
Cheers,
Brad
Edit: Shortly after posting the above, I realized that the H22 was not produced in 1988! Check your HIN to verify. Most likely, you have an H23 which was made from 1985-1992.