I'd like your opinions on two different approaches to providing a client need. We need to provide a simple RF control. This is not a security item, just a minor convenience:

A) purchasing parts and assembling them.
In the case I'm looking at now, parts are surprisingly inexpensive, but would need to be installed in a case and provided with a power supply. It's not Arduino but it's on that level. I can see the parts and labor, mostly labor to make it look professional, easily being $300.

B) purchasing off the shelf products.
This way, a complete chassis that does much more than the client needs would be purchased, hooked up with a few pieces of wire, and programmed. The price for parts and labor will probably be $400 for this approach.

A big difference is that with (B), someone else can come along later and troubleshoot and fix any problems, since there will be corporate documentation and the product is widely available to the industry. I think (B) is the more professional way to approach things, but people are sometimes twitchy about price, even if lower price predicts difficulties down the road.

We've all run into one-off custom jobbies where we had to figure out what the hell the product was and how to make it work again or reinvent it. What is your approach when asked to do something with these two possible ways to go about it?