Sounds like investing in a decent stringing machine is the way to go, so that you can quickly and efficiently restring on a regular basis once you get the hand of it.
And I agree with Maxpotatov that using dead poly is doing you more harm than good on many levels. Poly/gut hybrid or sub-$8 full poly that you frequently switch may be the best way to go.
If poly lasts you 10 hours then you're looking at $80/month in string costs if you supply your own labor, with a little machine depreciation tossed in. So perhaps $1200-1400/year.
If you were into motorcycle racing, you'd spend that on a quality helmet and a pair of gloves.
Are you also incorporating any training off-court?