As I'm sure many others will tell you, it's better to get a 500 chip cash set and a 500 chip tournament set instead of one 1000 chip set for mixed use.
For one, having premium clay chips adds a level of security to your game as the chips are harder to obtain than dice chips are. However, when you use one set for both cash and tournaments, this layer of security is gone. Not that you don't trust your friends, but it's all too easy to slip a couple of T25s off the table during tournament night, and then next week when you're playing a cash game, the chips magically reappear and the bank comes up $50 short...
Perhaps more importantly, using a combined set for both cash and tournament will both limit your options and increase the price you should expect to pay. For example, all of the Paulson clay chips that come to market here are either from casinos that never opened, rebranded, or closed. Since these casinos will have lots of primary and secondary cash chips, it'll be easy to find a cash set of $1s and $5s and $25s and a few $100s and $500s, but when you get into the higher demon chips like $1000s, $5000s, $25,000s, etc. these chips are in high demand and low supply, and sometimes go for $10-25 per chip, especially if they're oversized. On the other hand, casinos typically have tournament sets that you can pick up in the area of $1/chip, including the higher denominations, as the casino breakdowns will match the breakdowns that you need. Although if it's a relabel or custom set you're after, this constraint doesn't matter too much.