mingis - 9:46 am on Nov 16, 2011 (gmt 0)
Thanks for your responses, I will certainly check them out - in the meantime I've also done a bit of research of my own and found the following solutions:
X-cart - has a plugin which allows customers to create a quote from their shopping cart. It doesn't look particularly pretty but I'm sure it could be improved upon:
However the authors of this plugin advise me that most of the source code is encrypted so unless it does exactly what you want you will have to pay for custom development.
Magento - has a couple of options for creating and managing customer quotes.
This one which seems a bit over-priced and complicated:
And this one which is much more affordable and easy to use:
At this point I'm tempted to go with Magento, but thanks again for your input I'll compare them with what I've found.