I'd say definitely. Make it a selling-point and the insulation will only help to keep it dry. I'd even throw in a few plumbing and wiring future pipes. It might double your already minimal materials costs, but the floor never has to be disturbed by anyone...everyone likes that.
- Think, kitchen and bath or just hose bib, shop sink and toilet at a minimum. I'll stop raiding your nest-egg with Radonseal it. It's one & done forever (
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), just spray it on with a cheap garden pump sprayer. Nothing better and does what it says, fantastic stuff.