I had a similar issue - how to find somewhere affordable near Portofino? I ended up at the Portofino Kulm, which is way above Portofino (400 meters above - it takes 30 minutes to drive out to Santa Margherita and then up to the hotel from Portofino).

http://www.portofinokulm.it/eng/congress.html

Had a wonderful stay -- very charming with the restored 20s style, great views (you can see France on a clear day), excellent restaurant (run by Zefferino family who run many well known restaurants in Italy and Zefferino at the Venetian in Vegas) , and friendly service from the staff. You can do a very long walk up or down the mountain, but after one time, you will want motorized transportation. Cabs are expensive, so this is a great option if you have a car (or if you really want to live the Italian dream, a scooter to wind up and down the mountain).

Just checked the rates for your weekend. Looks like 203 Euros is the standard room, which is about 25% more than we paid a few years ago. But still probably better than some of the other options.