For a business with your volumes, you'll need to find an agency that specialises in Magento or another enterprise-level platform. Enterprise platforms provide integration with accounting software and are very good at handling workflow, stock control, reporting etc.
I've had an Enterprise platform for a few years now... most recently with BigCommerce. Thing is, it has to work with channel integration software - which has been getting better and better, but is nowhere near where it needs to be. I've been through three different suites of multi-channel management software, and none of them really works for us. Some of the problems include:
* our need for lot-tracking (we do medical) items that, once brought in, might go out the door as a component of one of several assemblies or as a stand-alone product.
* having three online channels that each employ different protocols - everything as to convert to some common language (currently XML)
* keeping track of not only what assemblies have been built, but also which CAN be built, considering real-time commitment of the assembly's components...
* ... and more
Sometimes I think there's a damn good reason that there are so few players in our arena. Growth is easy - staying on top of it - - not so much.
Forget about trying to save money by reusing theme code from the old site; web design has evolved considerably in recent years and you are better off getting the UX rebuilt from scratch and just migrate the inventory, customer accounts, orders etc.
True... I've done that twice already. But now it's getting truly difficult due to the size of the site, with all the associated web pages and shit. "Option" products don't make it any easier. All that stuff can be easily exported, but getting it to import without having to go back and tweak every single attribute seems to be nigh impossible.
You should consider finding an agency that is not only able to develop the site, but can also handle the hosting, updates, security, and backups.
That would be NetSuite. They're truly impressive, but hey - we're not Lockheed fucking Martin!
You may be able to find an agency to do a good-quality job for under US$25k, and perhaps $200-$300 per month for hosting etc.
Yup - that's what I'm seeing. BigCommerce is going to run us about $1200/mo after discounts, but they are making big promises about coming through with all the bells and whistles I've been asking them for over the last two years. There's no contract involved, so I am on the verge of deciding to ride it out with them for while and use the developer resources I already know.
Developers are ... less than reliable in general. BC recommended one company that went belly-up in the middle of a project, leaving me with a site that wouldn't scale for mobile apps. It looked like it did, but some critical functions like "add to cart" went missing from a lot of pages. Then there was one of BC's own ex-developers they recommended... all I wanted was some images retrieved from my previous site and imported and placed into the new site - and he managed to completely hose THAT up. Something I could have (should have) done myself. Recently I've had some minor work done by another outfit that was excellent and low-cost, but of course by the time the project was done, they'd been snapped up by another Company and doubled their rates.
It's mayhem out there, Bigfield!