In addition to comparing fares to other cruise lines, itineraries, cruise ships, time of year, etc...I compare the fares to a land based vacation, too.
For example, I'm in OH. I like Chicago. Spend lots of long weekends there.
A hotel, either around the museums or Michigan Ave, where all the activities are, is going to run me at least $200-$250/nite (at least for a decent one). Add in parking ($40-$75/nite). Add in food ($150-$200/day). Gas to drive there and back ...$100 (that's low, but I drive a hybrid). Activities (like Shedd Aquarium, Natural History Museum, Art Museum, etc)...$20-$40 ea for entry. Chicago River Tour is $54/pp.
So, let's say you stay 3 nites for an average cost of $225/nite=$675
Parking for 3 nites=$120 (minimum)
Parking at museums is $10 each=$30
Museum entrance charges (3)=$60/ea
Food=$450
Gas=$100
Total=$1,495 (and that's being WAY conservative with no drinks)...add in another $100 for the river cruise.
So, using that as a base, search for a cruise in that price range to wherever it is you want to cruise. More than likely, you'll find one with Free at Sea and free 2nd person flight. And, your cruise will include meals. You can do as much or as little, spend as much (or nothing) on board and at the port(s).
Is a balcony worth it to you? We don't know. Value is a personal measurement. You decide.
A little leg work will yield good results. Good luck in your search.