Assuming the reason you don’t want a spreadsheet is because
a)you want it to be branded and nice and not look like they are just hacking some numbers
or
b)you don’t want sales people to be able to mess up the sheet
then you could build an html5 web app, and either wrap it with one of the wrappers which make them into a native app (phonegap etc.), or use html5 offline web app stuff, which makes your web app work even when you aren’t online.
You’d need to know a bit of javascript / html / css, but that is a lot easier than learning proper app development or getting a full custom app. Easy enough to do for someone who knows any javascript (or is willing to google enough javascript to hack it together). How much work it’d be would depend on how complex it was and what other lovely features you decided you needed (product pictures or whatever).
It really would be quite easy, if you can work excel and do cunning stuff in it, you could probably hack something together.