so, these ones you can get for under six dollars at target, they come in a pack of four.the only size i saw offered were the 0.3 mm tip size which makes it fairly good for inking and detail work.
staedtler id a german company and from my experience has a good history of making quality products. i'm pretty sure i was introduce to the pens in college, my roommate and i had a coke vs pepsi debate between this brand and the microns. i eventually came around and decided to give them a try. the price is pretty fair, a little over a dollar a pen.
the triplus fineliner is a very skinny and long pen, the attribute that stands out the most to me is it's shape. it's a triangle. this feature was undoubtedly chosen to counter the pen from rolling out the table or shallow inclined drafting table. it unfortunately makes it awkward to hold, this may not be the case for everyone, i just found it a little annoying, the could have made 80% triangle and the part near the tip more cylindrical; or, barring that, put a rubber grip on the pen where its held..
now bear in mind that most of these pens are drawn on regular index cards, i did this because i wanted to show as close as possible how these pens work. that is also a factor in the sketches i make, i've been trying to limit the variables to the pen itself.
so the good: cheap, fine tip and won't roll off tables. the downsides are that they not only bleed, but also bleed through (gah! lame!) they don't feel comfortable in my hand and it takes ages to ink with such a small tip size.
in regards to the ink, i don't know how much use you'll get, i have pens from the same company that have lasted over ten years, granted i didn't use they all that often.
is it worth it? these pens may be a bit sturdier than the micron and copics, but the price is around the same. i did just buy these pens last night so maybe i should do an update on them when ive had more experience with them.