Can be anywhere from 100-1000 for me depending on whether the shows are rated or not and how many days they are.
My trainer charges around 50$ a day trailering can range from 50-150 depending on how far away the show is and ow many people I'm trailering with.
When I showed school horses, it cost around 25$ a day for them.
Show fees themselves can vary greatly.
At rated shows, you need your horses passport, your yearly EC membership (in Canada)$150, whatever yearly insurance is required by that show, to pay admin fees ~$50, fees for the division ~$50-$200, general registration fees 0-$50, fees for stalls ~$25-$50, fees for bedding ~$20-$70.
At training shows, it usually costs under 200 in total for the show because you don't go as far, and the prices are all greatly reduced.
You also need to take into account personal costs such as gas money and food.