Thanks to everyone for their input. As I mentioned before, due to certain time constraints, my hand was forced and I had to release early for one platform. Fortunately, I now have more time to work on it and will be able to release a "fuller" version with more features eventually.
What I ended up doing in the end was to use the booty as a sort of player level. There is a leaderboard the lists players with the most booty, as well as some other leaderboards that track the number of jobs they've completed by difficulty (such as "Most Easy Jobs Completed").
As for spending the booty, the user is given the ability to purchase upgrades that allow them to buy hints (useful as a last resort when you're running out of time), or to buy a bomb which clears a large section of the game board for a not-insignificant price.
In future updates I hope to implement customization of the player's ship as well as add some more competitive play aspects other than leaderboards, such as being able to challenge a friend or something like that. I'll also spice up the core gameplay a little by adding and tweaking certain elements.
What I have right now isn't the best solution, but it does give the game a bit of strategy so it isn't just the same thing over and over. Also, I've already gotten a few sales and had a user beat my own high score. As game developers, that's probably one of the most satisfying parts of playing our own games