You can already have a bubble of 10.000 LY's radius with 1.000.000 LS distance on each star system, which gives about 67,5k trade markets in your database.
The key to not let your PC explode is the Trade Range limiter, which defines the bubble of star systems around you and it updates accordingly,
when moving through space to other star systems.
The only disadvantage is the time required of updating all markets from EDDB. Here is an overview:
- Creating a market database (only a one time job): 6-7 mins, 11 MB registered market database size.
- Updating trade stations with all options selected (trade, outfitting and shipyard data): 7-8 mins, 98 MB commodity prices database, 335 MB outfitting database.
- Updating star systems: 1,5 mins, size is nearly the same as before (15 MB).
With a Trade Range about 1-3x your jump range you are good to go, but you have to spend nearly 10 mins. each day updating TCE before launching.