How much to charge?

[git]

Hiyas,

In the past year or so I've been professionally making websites (charging average yet competitive prices too since they are not easy jobs I get), and now I've came across a job where I have to make a point-of-sales system for a store. I'm a one-man team and I'm still at uni so I'm not what you'd call '100% professional', but I still know what I'm talking about, I get the job done and I do it well and professionally (better than some 'professionals' too, IMHO). I'm going to use VB since I know the language inside-out from using it in school and as a hobby.

The program must be able to scan products using a barcode scanner (easy), print user-defined barcodes, contain a database of products (with images), keep a record of customers (with a form of discount card/scheme), sales/trades/rentals of products, history of sales, etc.. The user must be able to of course modify/delete/add records (products/customers). The program will only be used on one computer at one store.

My question is, what's a ballpark figure that I should be charging? FYI I'm in Australia but a USD amount would be fine.

I've been told that $80AUSD (about $48USD I think) an hour is the minimum going rate for a VB programmer, and that I should guestimate how long it'd take to do the job and charge to the hourly rate. I'm thinking I'd take maybe 40 to 50 hours, but that'd work out to equal $3200~4000AUSD, or $1920~2400USD!!! I think that's a little high for a small store with only one P.O.S. terminal, but what does everyone else think? I mean, if they want it customized to their needs like that, *should* I charge that much? I have a fair idea of a price I will charge, but I just want to check this out on here first.

This is my first VB job but I *know* I can do it well (trust me - I have a *LOT* of experience with VB :P).

I'd be VERY interested to hear feedback from anyone in-the-know about prices.

Cheers,

Git