A DE 1000w Phillips bulb will retain 95% of its output after 1 year.
At $60 USD for a 1000w Eye Hortilux HPS, and even changing 2x a year is only $1200 in 10 years.
I get 4lbs+ from 1 crop 2x 1000w, at $200oz, is $6400 worth of weed. Add in $250 a month for 2 x 1000w on 12 hours, and 1 on 24. Say $800. 3 x 1000w all together
$60 x 3 bulb. $180 $250 Reflector/Ballast x 3 $950
$800 Electric
$950 Bulbs/Ballast/Reflector
$070 Promix BX
$1820
Say $2000
Still $3400 left over, and for some weed, $200/OZ is giving it away.
I could buy all new 1000w system every grow cycle, and if you can do 6 harvests a year, thats $20,000 worth of weed. After expenses. I get 6 in 378 days, with SSH. Been running this cut for 4 years. Been growing since 1972. 1977 indoors.