"The MAX" by BUDGE should be under $100 (I got mine on sale for $89.99) and protects as well as any I've seen. For long-term (as in "over the winter") I tied down a blue tarp over it as my Lincoln is parked under a shore pine = bird + resin.
Unwrapped it last Friday to give it a battery charge & a warmup: very happy with the results.
Paint looked dry & perfect (won't even have to wash it when Spring comes)
! Cover looks new, tarp seems fine, no runs, rips or delamination.
At this rate I estimate it will probably last 10-12 winters. Maybe more.
Results may vary : fit is important, if it flaps around in a high wind a lot it will probably have a detrimental effect on the life of the cover.
'91 420 SEL @ 199K, '92 SVX @ 181K, '93 SC400 @ 86K, '93 Kaw ZX-11 @ 30K, '87 F250 @ 181K , 2001 Valkyrie Interstate @ 6K, Y2K Honda NightHawk 250 with 1.5K, '88 420SEL I.@ 179K & the 2nd latest, an '88 420SEL II.@ 210K runnin' parts car, '85 F150 300/NP435