No. Charge them the minimum you can for hardware and software, then charge them a separate fee for support: factor installation and repair time into this support fee and set it accordingly. Basically, keep your chargeable services as a transparent labour/expertise fee, don't add stealth charges to the prices of the parts.
I'd never add costs onto the price of the actual hardware: because at some point a penny pinching accountant is going to check up on your prices and decide they can get a better deal by buying their own and paying someone to install them. Or they'll start questioning the prices and ask you to buy elsewhere: at which point your support charge may not cover what you need to do.
Set a fee, but make it part of your marketing that you never add to the price of hardware and software. A "we're honest, our price is all you pay us" line.
The only time I'd consider it any other way is if a competitor is using the same tactic to under-cut me, in which case I'd set the margin at a percentage to make the same fee as I was intending anyway. This can backfire, as mentioned above, if the client cottons on and asks you to use a different (cheaper) supplier, at which point your under-cut fee isn't going to support the work.
Keep it open, clear and honest, and your customers will trust you all the more for it. Too many companies are wary of tech support companies because of this very thing: they don't know enough about technology to scrutinise, so they fear they're being ripped off. They're normally right.
