I think you've already seen the question about tools for migrating VB6 to VB.NET.
Both have published special offer prices for the UK market on their basic products on this Microsoft UK page. Of course you need to know the limitations of the basic products and the prices for your market to make a realistic judgement, so you probably do need to contact them :(
- Artinsoft Upgrade Companion Developer Edition £199 for up to 50,000 lines of code. EDIT Now offering a free version that can do up to 10,000 lines of code.
- Code Architects’ Visual Basic Migration Partner Professional Edition £399. They told me this was also for up to 50,000 lines of code.
The built-in Microsoft upgrade wizard is pathetic - according to the guy who wrote it - of course he is from Artinsoft so he wants to sell you something better. Microsoft UK also say the Artinsoft and Code Architects tools are better than the built-in upgrade wizard.
EDIT: I contacted Code Architects for a quote, they responded very fast. Unlike this Stack Overflow question by Angry Hacker who had a worse experience. But then Francesco Balena popped up on Stack Overflow to answer his question within 12 hours, which is more encouraging.