Its not a bad system all in all, and if cost is the main consideration I would just replace the keypad.
Be warned there are two types of keypads available - 4 wire & 6 wire ,depending on how old your panel is, it may only accept the 6 wire version (6 wire now obsolete but I've seen an odd one listed on eBay)
The newer versions accept both the 4 wire & 6 wire keypads.
They do a blue LCD version now which looks good.
Do you know when it was installed?
Have you more than one keypad?
Do you set with Gtag Fobs or an ACE?