Watch Ebay for a used tiller pilot. If you wait long enough, you should be able to find one for under 100 bucks.
For several years I sailed without it, and it was always a scramble getting the sails up and down. The limitation is that even if the boat is under power, walking to the front on that small of a boat will make it change course. Wind shifts would also make it change course. Rather than bothering with a tiller tamer, I just screwed a cleat to the bottom of my tiller. Looped my dock line around it a couple of times, and that would hold the tiller straight. But just because the tiller was straight, doesn't mean the boat would stay straight.
Something else that will help a lot is to rig some lazy jacks to your boom. On a small boat, you don't have to go crazy with all the pulleys and such, just create a "basket" to stash the sail in as it comes down. Mine is set up so that it is loose under sail, but when I drop the main, the lazy jacks catch the boom and hold it just high enough to keep the boom from hitting the cabin. This pulls the lazy jacks tight so they can catch the sail. This saves a lot of time, so that you can stay on the tiller longer.
The last thing I did was get rid of my outboard and opted for an 86lb thrust trolling motor. The trolling motor is so much more dependable and seems to control my speed and direction much better. The trolling motor is set up for torque so you have greater control at slower speeds. You can't beat docking with electric. Surprising how much that changed my sailing experience.