Web-based Project Management for me and the clients?

I am developing my website to the membership area part which will enormously help me and my clients communicate through web-based channel, then I come to the dilemma whether should I hand-code every single part of this project management tools myself (which I don't have much time but I prefer perfection, very nice user interface, and well-rounded functionality) or should I seek the abundant paid tools which are available but expensive out there on the Internet. I do like Solo (thrivesolo), its interface and functionality, seems to answer almost of my basic requirement but the problem is Client access area part of their site isn't implemented yet and lack of some features I need. My question are:

1. Should I develop my own project management tools myself, is it worth it? As I don't seem to find anything out there which fits my entire needs: client login, file sharing and display (upload and download), questionnaire management, basic support features, insert some products for them to choose and pay, and billing section for them to pay the invoice.
2. Do you know any web-based project management software out there which provides everything I've just described with free trial period at least and must have very nice user interface like Solo and Basecamp?

Hey Modular I ask myself this question every week and still struggle finding a system that really fits how I do business and work with clients. There is no one system that fits everyone. Basecamp has a new version coming out in a few months that is supposed to be awesome. I hope it is.

I'm currently using Redmine it's open source, built on Ruby on Rails.

Allows me to setup projects, allow client access, has file upload, can allow clients to submit tasks / tickets. Also allows clients to email an address and it will auto put that in Redmine as a task. That's pretty sweet, and it a plugin.

I then use Freshbooks for doing all billing and invoicing. (Cashboard is also very nice)

And Wave Accounting (free) for doing my reporting and track expenses and log income etc.

Recently I have been using Asana to do client to-do lists for projects with lots of little items or to break a project down. It's cool but lacks lots of other things.

Depending on your needs you might be able to get away with just Freshbooks.
It allows for client support tickets and you can put files out there for clients.
Both those features are primitive but may be enough depending on your project complexity.

They also have an API so instead of coding a project from scratch maybe work on some integration? So pull your client invoices into Redmine and show them there to make it all look integrated.

Basecamp also integrates with Freshbooks

Good luck!

Have a look at HappyTodos - it might fit what you are looking for (disclaimer: I work there :)). It's completely free, and has all the technical functionality you could possibly wish for (really. I've tried tons of tools, from basecamp to simple lists like doittomorrow, and HappyTodos does everything I need). It's a bit rough around the edges UI wise, but we're coming out with a new version very soon.
http://www.happytodos.com