I believe that if you're paying out of pocket, Lantus & Levemir will cost around the same. If you have insurance they may have different co-pays for the two if one brand is preferred. I know my insurance won't even cover Lantus, only Levemir. NPH is cheaper and does not require a prescription. If you are near a WalMart, they sell it under their Relion brand (it is actually Lilly's version of NPH, so it's actually a brand name even though it says Relion). I think WalMart charges around $25 for a vial of it. Speaking of vials, they are cheaper than pens. Instead of screwing a needle onto a pen you would need a syringe to draw up the insulin. Also, many people reuse pen needles or syringes. Before I got my pump, I would just leave the pen needle screwed onto the pen and put the little cap back on it. I'd use the same needle for an entire cartridge and I was using Humalog, which meant multiple injections a day. For long acting insulin (I first used NPH, then Lantus) I always preferred the vials. I didn't need the convenience of a pen because I was always at home when I took long acting insulin. I would recap the needle and reuse it multiple times.
Some people find little to no difference between Lantus & Levemir. SOme may need to use more of one over the other. Many people do find they need to inject it twice a day (either Lantus or Levemir).