hi tough question to really answer, is the unit all lace or psb (poly on sides..whats the density higher then 70% ..do u sleep in it ..how often u shampoo it a week..
i wear 65% density with poly sides and back tape all around..

my answer if i dont wash it 2 much and with all my experence alot of wearing 7+ yrs and i sleep with it on . wear 24/7 i avg 3 months...many claim 1 year ....but if u baby it and have high density it will last longer. and i i have stated long ago u shold have a back up right now unless u dont need one....many sat mornings i was rushing with clean up and ruined (riped my ) best units over the years.. i have at least 2 backups and 10 old units i could use if i needed to...i will never tap into the old 10 beatup units but i can...i would guess 5-6 units a year would give you nice leway....also low density shed easier to look balding..but i think u are a young guy right high density..simple math 6x 200 = $1200 yr max less the avg cell phone bill to look your best..many wear french lace and get 6 months. i know as i wash the unit less and just wet it i get much longer use....ask any questions i will answer if i can
bobby/philly