I just totaled this up. We have a 20 year old Safari with a CAT 3126 motor and an Allison transmission. We've owned this for 2 years and I do most of the upgrades and leave the oil changes etc to the shop.
1. Replaced rear view camera and monitor. $215
2. Replaced old shocks with Bilstiens. Added valve stem extenders. $1550
3. Major go-over before 6 month winter road trip. Oil, filters, trans oil change, chassis lube, rework turbo tubes, fix valve cover leak, clean CAC and radiator. $3500
4. Replaced exhaust pipe. $500
5. CAT service, valve lash adjustment, oil and filters, chassis lube, belts replaced. $2500.
I had a few misc. parts to buy (Norcold burner, toilet parts, Fantastic fans) and a roof leak that needed attention on the trip for another $1000 or so.