Custom Product Builder For E-Commerce Site

Hello, We are looking to update our website and move off of the existing OSCommerce 2.2 Platform our store is running on. We are looking if possible to move to a Magento based store. Our store currently has a custom product builder / quotation page which we need to have re-written and revamped in general. As it stand we are starting to have a few issues with the existing page, mainly with errors appearing, selections not being valid, prices not being generated etc. Having said that it has served us well until now. We have been looking at some of our competitors and have come across a similar type of quotation system which we would like to have replicated with some slight modification. The competitors page can be found here "[login to view URL]" Our own site is "[login to view URL]" and our quotation page can be found at "[login to view URL]" One of the primary requirements is for customer to be able to select Different quantites of their choosen product, we currently offer quantities set out as 10 ,25, 50, 100, 250, 500, 1000 etc etc. We would like to keep these quantites as options but also allow the customer to enter a random value for example if someone wanted to purchase 333 units of their choosen package then have the price automatically update on the quotation page to reflect this (This option is available on the competitor site.) We also wish to keep the ability to click on products which we place on our homepage and add them directly to the shopping cart. (For some reason we do not have this ability on the existign site and if we attempt to make an external reference to a product ID then we end up getting a mySQL error.) This project will hopefully be approved in the coming weeks and ideally we would like to have it completed by the end of November at the latest. If you have any questions then please contact me and I'll do my best to answer them. Thanks for your time, Reagrds, Bill