I would think it easier to go cheaper with panniers than a trailer. I find the Nashbar waterproof panniers you mention to be quite adequate and have used them for a number of long tours including a Trans America.

I will also mention that if willing to somewhat minimal in packing style, just strapping on a couple stuff sacks can work well. I know that I managed to do the ST from San Diego to Sarasota with two ultralight stuff sacks and a road bike. That was with a very trimmed down list, but it did include camping and cooking stuff. I didn't find that I missed anything and had a great time. That trip the base gear weight was 14 pounds and not everyone would be willing to pack that light, but there is a middle ground where you could carry a bit more and still use the basic approach. FWIW, I have found it possible to even go a good bit lighter than that and still maintain what I consider reasonable comfort, and that still without using much specialized expensive UL gear (no need for cuben fiber or other similar high dollar high tech stuff).