It's difficult to tell without pictures, but good starting point would be to look up online auction sites and seeing other copies of Torchic Gold Star (namely, finding ones that resemble the same condition). That'll at least give you SOME ballpark of what you're looking at.
PokeBeach also has a discord chat, you could try there.
Here's the thing though, unless you are desperate to get cash in hand, I'd hold onto the Torchic Gold Star because their values are only going up. I've had a Celebi Gold Star since 2017 that I found for $35 online (auction sites had it for about $50 at the time). That things value has shot up drastically--and it's like, the cheapest Gold Star if you were to go after any of them.
Torchic Gold Star was also one of the first Gold Stars, so it has a bit of that "historic value" going for it--even if it's played.
But yeah, try posting a picture in the PB Discord and ask there. There are people more familar with Gold Star values and card condition/price than me.