Re: Stripped under sink shut-off valve.
That is a PEX style waterline, which is flexible plastic and crimp fittings. Without the necessary crimping tools, there is no removing the old to install the new. Since you're on a budget, I would attempt to replace the guts with those of a new valve. New valves will be found at a mobile home parts supplier or repair facility. Mobile homes are a unique breed so you won't find off the shelf parts at the local big box supply.
Look in the phone book under mobile home parts, repair, service, you should be able to find a number of local businesses and repair personnel to help you.
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