I'm more of a mechanical pencil guy, and my daily carry is the Pentel P205 (0.5mm, the black one). I bought mine on eBay for $6 from Korea a few years ago, and I've been using it daily ever since. In year 11, my pencil tip was damaged somehow, and I asked Pentel if I can buy a new tip, and they sent me a new pencil for free. Here are some notable mentions:
- Pentel Techniclick (~$4 at Officeworks)
- Pentel Sharplet (~$4 at Officeworks, tip lasts exactly 2 terms before cracking. This happen to me twice)
- Pentel GraphGear 500 (~$15 on eBay)
- Staedtler Mars Micro (~$10 at Officeworks)
- Pentel STEIN P315 (~$10 on eBay)
All prices are in AUD. If anyone has any questions in regard to mechanical pencils, please let me know. Sorry, I just realised you asked about pens...I use the Pilot BPS-GP (~$4 at Officeworks). It's a really comfortable, and smooth ballpoint pen. Some may also recommend the Pilot G2 series, but I don't really like gel pens. I carry a Parker Jotter with me everywhere I go.
edit2: I used to export 5-cent pens from India by the bucketload, they were my besties in year 12
My grandma sent me heaps of pens from Sri Lanka and they were really nice...can't find them here. Next time I go, I'm going to also buy a bucketload.