A couple of points:
1) You will save money paying your tolls electronically, there is a discount. It varies by road, but on the Greeneway 417 route from Sanford to Disney, the discount is $.99 one-way, so if you do it round-trip, you essentially save $2.00 (The current toll for that distance is $8.00 cash, or $7.01 with a toll pass.)
2) With what you are spending on gas, floating $10 on your Sunpass account is really not worth stressing about. It won't expire, it will sit in the account until you use it. Besides that, you'll save gas not sitting in traffic.
3) If you REALLY don't want to auto-top your Sunpass account with a credit card, it is possible to pay it at Walgreen's stores with cash, and there is no minimum on cash payments, so if you just wanted to add $3, you could, though it would take you some time unless you were planning to stop at a Walgreen's already.
Here is how I look at the issue of toll roads while I'm on a vacation trip: for any moment of the 40 hours per week when I would normally be working and earning, I'm not earning while I'm on vacation, so I balance what convenience factors cost me against my earning rate, and if the time savings costs me less than I would earn in the same amount of time, then I just pay for it. A nasty pileup delay on I-4 taught me that lesson, when we sat in traffic for several hours on one trip. In the equivalent of paid vacation time that DH and I lost to that one delay, I can pay my average Orlando-area road tolls for what I estimate is probably 4 years' worth of trips, including the $20 cost of the portable transponder we have. Using the transponder lowers the toll cost, and I don't have to keep track of change for the unmanned toll gates, either, so I consider it a small price to pay. There is currently a balance of $10.61 sitting in my SunPass account, bless its tiny little heart.
PS: If you will be using a rental car at any point, it is better to invest in a portable unit instead of the fixed sticker.
