I'd say double what you expect to pay, it always cost more than you think. Don't forget little things like misc nuts and bolts, shipping costs, beer and food for your friends who help, grinding wheels, extra axle housing because you find out yours is bent, etc.

Eventually you'll want to either go all pro links in the rear or leaf springs and that's another $700. Your stock links won't hold up too long with the extra lift you'll need to match the front.

I have $700 in drive shafts alone because I wanted to be able to drive in 4wd faster than 20 mph. To do that you have to pay attention to your driveshaft type and angles. You'll need to go with a CV type front driveshaft but since they can't accommodate the angles needed for articulation you'll need to upgrade to a high pinion diff (or dual transfer cases, but that's a can of worms since you have an auto). At that point you might as well pony up for a locker too.

See where I'm going with this? It costs a lot more than you think it will.

On the other hand, considering you've destroyed your IFS, I do think it's time you upgrade. If you decide to do it, I'll be glad to help you out if you have questions.