I have a second hand 2000 to 02 factory rebuilt 2.7 that I just put in my 01. I bought it on Ebay for $2500 shipped from LA. Just got it started this past week and it seems to be pretty good. The engine seems to have been reman'd after 05, it has the later IMSB installed.
You can probably still get factory reman'd 3.2 engines from Porsche. I don't know what they cost, but I'd guess you'd just as well have something from Raby--who last I check had engines that 'started' at about $15,000.
Used 2.7's are pretty common. I don't know about 3.2's.
https://www.ebay.com/sch/porsche%20boxster%203.2%20engine?rmvSB=true