Why not keep UAG as the only case? It will offer both style and protection, all around the day. Also, keep in mind, no matter how great UAG is going to be (I'm waiting for Navigator as well), taking it on'n'off every single day along with an alternative case will wear it's off sooner or later. A cheaper and more flexible TPU case will have a greater longevity, but obviously less protection. I'm just guessing UAG will be more rigid and after constant on and off might form cracks.
Regarding Trident, $19 is probably the best you can get until Note 3 is released, unless if they are slow sellers and have special one-day promo deal.
Since you are saying you trying to save money, I would just stick to one case
