I have for you the cheapest way to modify your PC. My current mod is incomplete but it will give you enough information and ideas to start your own with no more than a can of spray paint and metal tape.
First get a roll of aluminum tape, it is the best thing for a budget mod. for that stainless steel look get some fine grit sand paper and take long snow strokes down the tape in the same direction and when done polish with some Brass-O.
Step 2: Hard Drive Status Gauge
Now for some heavy duty moding. Find an electrical gauge, then a place on the PC it will look good. now cut a hole to size and affix it in there with some hot glue. If you like me do not have some of the proper tools, draw out a circle to cut. then use a series of small drill holes cut as close as possible to each other.
Now to wire the gauge, find the wires that run to the blinky light in your PC front and cut the wires and hook them to your gauge. If the gauge goes straight to 100 or what ever is the max, get some resistors to go between the positive wire and gauge so soften the blow.
Now for some Brass. Brass is to the unknowing will seem expensive, but just head down to the local hardware store and pick up a brass door plate. It is perfect for this project.
Now with plenty of WD-40 sprayed on the hack saw, cut the brass plate to size for whatever you may want and affix it to the PC with screws or Hot glue.
If desired get some Brass or (in this case)Copper spray paint and go at it what ever witch way you please. if plastic or much else for that matter is to be painted cover with metal tape ten apply one coat.
With what you have now, you PC is now Steampunked to atleast some degree. Now add what you what: leather, brass, leather straps, bolts, ANY thing old!