Betsy- if you are running an SET with 18 watts, you need more efficiency than 92 db to really hear what the amp is all about. One inexpensive way to get that is the ZU Druid- but if you look into them, make sure they are a new pair or a set that has had the recent updates, else make sure that they are priced so you can get the updates.
Audiokinesis has made easy to drive speakers in the past in your price range, you might try with them.
Another approach is to go with vintage- I recently sold a set of Altec Siennas that were 97 db 8 ohms. Although not much response below 40Hz, above that they were fabulous. I sold them for $300.00... I could have gotten more but I have too many speakers laying around :)
Audiokinesis has made easy to drive speakers in the past in your price range, you might try with them.
Another approach is to go with vintage- I recently sold a set of Altec Siennas that were 97 db 8 ohms. Although not much response below 40Hz, above that they were fabulous. I sold them for $300.00... I could have gotten more but I have too many speakers laying around :)