It appears to be in good condition, and I would consider that a good price for an Antares, especially with matching leathers already included.
Is is the correct size for you horse and you? That's the important thing to think about first off. Also, there's other saddles out there for good prices, and in similar quality to Antares. What leads you to Antares?
They're fabulous saddles and will last you forever. Super comfortable too. I wouldn't hesitate at the price. You get what you pay for, and with Antares, that's a positive thing.
Except, you can save up a few hundred more dollars, and buy a brand new Antares.... Hampton Classic by Antares - New Horse Tack from SmartPak Equine Spooner by Antares - Close Contact Saddles from SmartPak Equine
But I would consider it a good price, just make sure, if your willing to pay for it, there are other brand new options...
Also, was it a custom saddle for someone, or was it bought off the shelf? If it was originally ordered custom for the original owner, that can up the price. I've never figured out why, since once it's sold, it's not custom anymore, but a custom Antares will run a good $6000-$7000. That is something to think about also, when you trying to decide if it's a good price or not.