So yeah......
I had the reverse situation. I bought a super nice 3 person tent for backpacking (Nemo Losi 3P) with the wife and ended up getting a cheap 1 person tent for bike touring. I bought the Eureka Spitfire 1 and have been beyond pleased with it. It can be had for 100 bucks on any given day online. I think retail is about 130.
When I first got it, I hit a few suspect spots on the fully seam taped fly with some seam sealer. It has since housed me during some intense downpours without a single leak. The (gasp) nylon tafetta floor has been fine. Bathtub construction and taped to prevent any leaks, it has performed flawlessly. With lightweight stakes and a light stuff sack for the body+fly. the whole thing comes to 3 pounds. When I shopped around, spending 3 or 4 times as much would have saved me maybe a pound. Proper care will make any decent tent last a long time.
I think I might do a bivy bag one day depending on the adventure of choice. But for now, a nice double wall tent for warm, humid climates like mine seems to make the most sense.