Hi yah Mate,
I built my own, I couldn't justify parting with so much money they want for some shelves and there not to your specific requirements.
Get in the back of your van measure up! then go down to B&Q get some 12mm Plywood and get the instore machinist to cut it to size for you, then buy some self tapping screws, securing brackets NB:(very important to understand how much weight & stress your shelves will be under) Then erect them to your own personal requirements, sand down & varnish etc.
All in all it cost me about £70 to buy and about 6hrs labour.
Regards,
Rob.