I have a line on a re manufactured Yanmar 3GM30F. The info I have received is that the shop has replaced everything except the block. The price is $3900 and comes with a two year inclusive warranty.
I can't find a new 3GM30F or 2GM20F as these have been replaced in the Yanmar catalog with the 3YM20 and 3YM30 and I can't find a price for either of these engines.
For new I have found a Yanmar 3JH3-E that has 40HP but the weight is 100Kg more than the current engine. A couple Westerbeke 30B three's that weigh less than the current engine but output 27HP. A Volvo Penta D1-30 with 29HP that weighs just a little more.
I can't seem to track down an active owners group for my boat so comparing setups isn't going to be possible.