The only reason I want to get my own is because I don't want to use the public one at the gym... is that reasonable?
Yes, it's reasonable to buy your own equipment and bring it if the gym doesn't have one that's suitable. Most gyms do not have a problem with it unless it's destructive in some way (dip belts are pretty harmless).
Buying your own dip belt can have these advantages:
- It's guaranteed to be one you like. Some dip belts are just poorly designed.
- It most likely will be in better condition than the one at the gym. Dip belts tend to be very robust anyway, but the chain links and clips can wear out over time. Gyms can go weeks without replacing or fixing it.
- You'll have one if you ever go to another gym that doesn't have a dip belt.
- It's only got your germs on it and not hundreds of other people who use it.
- You have to pay more money for it. Though it is a one time purchase.
- You have to carry the thing around.
- You have to make sure you remember it on the day you are going to use it.
- You have to protect it from other people who may try to use it. Either they think it's community equipment for everyone or they're just jerks.