Basenji - You might be able to save $1k by doing it yourself but no where near worth it. Depending on how high your roof is, you will be lugging those bundles up a ladder unless you rent a lift ($200), you know you have leaks so you will also be lugging sheets of plywood up a ladder (very hard with two people).
Contractors get better deals on the shingles saving you $$, and usually have a team (4-6) working that can also knockout a decent sized roof in about 5 hours - taking off the old shingles, fixing damage and adding new shingles. It seems storms keep popping up all of the time so you want to get it replaced as quickly as possible. One heavy rain could cost thousands in repairs.
The little things can cost you a fortune in DC (shingle delivery, ladder rental, lift rental, trash removal, magnet roller) most contractors have all of the tools needed to cover this in house.
Our experience in Toronto is the polar opposite of about everything in this post. Not to pick a fight but...
Buy from a decent roofing supplier and you still get delivery to the roof. Including all materials, No one humps everything up a ladder anymore. Yeah, you may be off by a sheet or two of ply, but with planning, you shouldn't humping loads of materials up to the roof at all.
We can knock off a good sized house with a team of three by stripping on a Friday after work and installing Saturday-Sunday. As for storms, watch the weather - not rocket science.
Trash removal is a bin rented for a weekend. The only disposal purchase should be tarps to catch nails/debris. When I tear-off, its one dude on the roof and 2 on the ground. The ground crew is clearing into the bin as fast the roof dude is stripping.
Tools to own will include:
Gloves/kneepads/glasses - PPE
Tear-off gear - a shovel/garden fork, tarps.
Roofing jacks and walking planks. (Maybe rent - I got mine in a pawn shop for $10)
Air compressor/nail gun (maybe rent? Depends how often you will end up doing this, but nailers are so cheap now, why not buy.)
Skilsaw for cutting plywood
Chalkline, knife, screwdrivers, tinsnips
Ladder to reach the roof - preferably with stability wings at the top (Maybe rent, but I use ours every year for gutter cleaning/christmas lights/etc.)
Rentals Air compressor/Nail gun (??) see above.
Ladder - See above
Roofing Jacks and walking planks (See above)
Disposal Bin/Magnet
Material purchasesShingles
Fasteners (Nails or staples)
Replacement vents/ridge vents
Caulking (look for the stuff for roof work)
Sheet metal flashing
Ice & Water Shield
Plywood for deck, lumber for fascia/soffits if needed
Do the math and compare. In our case we found that even with the costs of stuff above (much of which we already own) the sweat was worth a lot more than $1000.