If you're looking to get into watch modding for the long term, I'd recommend skipping the all in one kits and saving up a bit more for a slightly higher quality tool set that that you're less likely to replace. The great part is that it's probably not as expensive as you think. The items I list below are not the ultimate best quality, but are SIGNIFICANTLY better than average, and you will likely never need to replace unless you get into cleaning/restoring movements (in which case you'll probably only need to replace the screwdrivers which are already cheap). The "Bare Minimum" below should cover 90% of your needs.
Bare Minimum (for just switching out parts / general maintenance)
from Otto Frei / Esslinger:
1. 4x ASCO Loupe - $20 - super good quality and fine for most of your needs.
2. Loupe headband by Bergeon - $5 (you might be able to hold the loupe in your eye without this. I can't)
3. French Screwdriver set from Ofrei (sizes .60, 0.8, 1.0, 1.2, 1.4mm) - $28 - amazing quality for the price, supposedly close to the quality of a Bergeon set.
4. #2 Stainless Steel Antimagnetic Tweezers by Dumont - $22 from Esslinger. If you're careful these will be the only tweezers you'll need (e.g. no brass)
5. Hand Removers (lever style by Horotec - $36 - much more reliable than the cheap one you squeeze
6. Hand Setting Tool (blue/yellow no-hole tool by Horotec for seconds hands, orange/black tips by Horotec for minute/hour hand) - $30
7. Springbar tool - ("First-quality spring bar tool" on ofrei - It's supposedly an unbranded Bergeon version and high quality) - $25
8. Case knife - for lifting bezels or opening snap cases - Bergon knife - $25
9. Blower - use your mouth. Just kidding - Bergeon is only $12, but I use one intended for my camera lenses, you can probably find a cheap generic one on the bay.
10. Bracelet resizing tool - I actually don't use one of these, hopefully someone else can chime in.
Subtotal - $203
Things you can buy on ebay since you don't need super high quality versions
1. movement holder - copies of the Bergeon one. You may need to sand sharp edges, but you'll get a large and small - $10 (however, the bergeon versions are not significantly more expensive than these)
2. Jaxa opener - get the one with three pegs, not two $12
3. Third party Rolex Opener - $20 - in case the ball doesn't work. You'll want to cover the caseback in thin plastic before using to avoid slippage / scratches
4. Watch case holder - for leveage when opening the caseback - get the yellow plastic kind with white pegs - $10
5. Case / Crystal Press - blue one with silver handle and white plastic dies - $14
Subtotal - $66
Consumables (buy form ebay/esslinger/ofrei)
1. Stick of Rodico - $9
2. Silicone Grease - $5
3. Dial Protectors - aorund $5 for 3
4. Finger cots - lil' prophylactics for your fingers. I buy them on ebay for about $8/100. Make sure you get powder free ones.
5. Blue loctite - $6 for those pesky bracelet screws or crown tubes.
6. Pegwood - $8 - much better than toothpicks
Subtotal - $39
TOTAL for Bare Minimum - $308
Extras (for case shaping)
1. Dremel 4000 - $70 (get a kit with sanding drums and cotton buffing wheels). This jabroni was $100 back when I bought one.
2. Dremel Flex Shaft - $25 (you can probably get a cheaper bundle if combined with dremel unit). Trust me, if you're reshaping crown guards, you'll have WAYY greater control holding this.
3. Swiss Vallorbe Needle Files (try to get "barette shape", it has safe edges, and a flat cutting edge that's versatile), they're very cheap and super high quality on esslinger. You can get #4 or #2 cut $7 each. You may need different shapes for your needs, but the quality of these blew my mind for the price, compared to those 12-files for $10 sets on ebay/amazon.
4. Dialux Green - $8 on Amazon for final polishing
5. WEN 8" drill press from amazon - $75 for if you want to enlarge lugholes
6. 400- 300 grit sandpaper pack form amazon - $10
TOTAL: $202 for Casework tools
If you want to get into reluming hands, get an $8 yellow Bergeon oiler. I've tried other oilers, but something about the shape of this makes it so much easier.
The veterans here should feel free to chime in on any recommended substitutions, these items are just what have worked for me and I've been very happy thus far.