Try attracting regular users by offering the service for free... Seriously. Because it is a web-based app the marginal cost of supporting users is very low, so the model I would adopt is start off free.
Word of mouth...
If you cannot gain traction by offering the service for free, you'll not be able to do it by charging 60Euro a year. Often awareness of a good app is spread by word of mouth - so it follows that if you get hundreds of users on your platform using it for free, you will have a base of people that (if the product is good enough) will rave about it to other people. And personal recommendations are the strongest. Hand out free accounts to the first 100 people and see how you get on.
These early guys will also be invaluable in providing you with feedback on what part of the app they like, and what parts could be tweaked. You may find that they are requesting some really neat features, and that actually the way to do this is by...
Adopting a freemium model... You've heard of it before - a product in a basic form is given away free and then to access some of the neater or enterprise features you have to subscribe. The reason this works well is that you gain a large base of basic users (getting it for free) and they do three things:
- They tell other people about it
- They tell you all their ideas on how to make it better
- Some of them realise they need a little bit more and pay you for your next-level-up package
Then it all becomes about giving the free users just enough functionality that they are happy (and raving about it) but then not too much that you are scratching your head for what to put in the premium (paid for) version. There has to be something really compelling about the paid for version for this to work otherwise nobody would shift from the free version.
If you can afford to try freemium... it's a good way to go. It is much easier to market and gain PR; get people blogging about you etc if the service is compelling and free. Once you have a good critical mass of people using it and enjoying it, then start thinking about monetizing it. By then I'm sure you'll have a good idea as to how much of a money-spinner this is.