A list of very good inexpensive fountain pens.
These are all pens I've bought and used myself, and for the most part continue to use. I also have more expensive, and fancier, pens. These are all well made and inexpensive not because they're terrible but because of the magic of mass production.
1. Disposable Pens
1.1. Pilot Varsity
1.2. Zebra Disposable
2. Cartridge Pens
2.1. Pilot Kakuno
2.2. Platinum Preppy
2.3. Platinum Prefounte
2.4. Platinum Plaisir
2.5. Lamy Safari
2.6. Pilot Metropolitan
2.7. Pilot Prera
2.8. Hongdian Black Forest
2.9. Pilot Explorer
2.10. TWSBI Swipe
2.11. Lamy Vista