It depends. Timing a coverage are important. I have successfully terminated poison ivy following these recommendations from the University:
Cut poison ivy vines 2 to 3 feet above the soil surface or in fields at least 1 foot. This will kill the portions of poison ivy above the cut. The remaining vine can be treated with concentrated glyphosate. A glyphosate concentrate (approximately 6 to 12 oz of a 41% glyphosate solution to 1 gallon of water) can be used to treat the cut portion of this stem. It is recommend to paint the fresh cut with full strength glyphosate solution or a 50% dilution in water. This treatment should occur within 48 hours of cutting the glyphosate vine. If any regrowth is seen, it should be retreated.
If vines are growing on trees, one should not be concerned if treatment is occurring on trees with mature, course brown bark.
I use a rotary cutter set high, followed by spraying the concentrate using a UTV sprayer. I had to repeat the process a month later to get good results.
Tractor suppy used to be $150 or even more a few years ago for 2.5 gallons.
Poison Ivy, gly works. Add some 2,4D if you can to it. Gly aloe will kill your leaves, but may grow back. Atleast 3oz/gal using a hand srayer.
Triclopyr would be better. But has ground action more stornger than 2,4D residual action. Also poison ivy burrows its roots into trees. Could be hurting the tree, if it's on one.
Just looked in my basement. A few years ago when someone on here made a post talking about how the price was shooting up everywhere I went to a local place and they still had 5 gallons for $40. Out here in the sticks, the price increase hadn't hit yet. I bought all they had. Those days are gone, but I'm glad the price has backed off a little bit.