I don't know what brand the disposable ones are that I like...they appeared in the lab when someone in the office ordered them, and are nice for a ballpoint pen (little bit of cushiony grip, and smooth ink flow, not that dry, scratchy feel a lot of cheaper pens have). If they haven't all been swiped by the pen thieves, I'll look for one later. I think those are Bic pens.
Otherwise, the one I prefer isn't a "cheap" pen, but it isn't that much compared to the more expensive, "fancy" pens. I like the Dr Grip pen. You can get a variety of types of ink for it. I prefer the rollerball pens (they do have a fine point as well as medium point...I like the bold lines of the medium point, but if you prefer a fine point, they have that, which can sometimes be hard to find in a rollerball), but you can also get it in a ballpoint version. These are refillable. Here's an example.
https://www.amazon.com/dp/B00006IEC0/?tag=pfamazon01-20
Ink is reasonably priced for them. When writing a lot in a day, it's really nice to have that soft, cushiony grip (one of the softest grips I've found...most are a hard rubbery plastic, this one has more of a squishy silicone), and the pen has a nice weight to it. The other nice thing is the ink isn't that runny, drippy, typical rollerball ink that smudges on everything. It's a little thicker, and more like a ballpoint ink (ah, looking around, it seems they call it a "gel ink"). The only problem I have is keeping away the pen thieves. But, it looks enough like a "good" pen that people usually realize you expect to get it back.
They also make a cheaper pen that uses the same ink, so if you want to get a $1-2 pen to see if you like the ink first, they have those.