15 to 1 ????
The only way to get close to that figure is with cheap unmanaged switches (8 port GbE switches are under £10 new on eBay) and count all the cost of cabling as part of the support cost. Most managed switches and routers are only reconfigured a few times before they are replaced so given their much higher purchase cost, the support cost should be lower compared to the purchase cost - unless of course the manufacturer provides such buggy software that an expensive support contract is a necessity.