Don't fall into the trap of getting quotes, then speccing the hardware yourself for half the cost.
The reason why companies quote so much is for the support of the hardware.
After fitting the gear and setting it up you go on holiday for a week and it all goes down, it'll all be down to you to sort out, whereas a professional job means that one phone call later and a support guy/gal will be on hand to fix it up, while you are still on your holiday!.
Just a basic heads up really, there is a reason why costs are so high for professional services.