I import consistently, and have for years. But I also am working on a business now so I don't use third party importers. There are many places that will order you in a box of stuff, and many of them all come from the same importers. I'll explain more about it, and don't mean to discourage but just to tell it how it is with importing.
First, those prices are pretty high, 600 is stupid high. These places that sell trans ship boxes to hobbyists tack on a big commission to the inbound freight and to livestock. With their bump in livestock prices and import charges once you get to 300-400+ then paying FOB freight to whatever airline you get it from at your airport, plus mortalities you're paying close to retail or more.
Now there's other questions such as,
Can you handle 20, 30, 40fish at once? Can you acclimate and quarantine that many? Can you provide enough live foods if they don't take to frozen? Not a single wild fish I've dealt with(skin scrape or internals always has something) has come in clean, and being packed into a closed system can make for a disaster, so they need special attention. I've worked very hard to get mortality rates quite low, but it isn't hard to lose half a box of newly imported specimens. Between their long shipment (well, 2 shipments back to back) ammonia exposure, and stress of collection a week ago being packed into holding systems they're incredibly touchy and risk of illness and death on arrival is high. People think getting "new" fish from the LFS or an online shipment to eat is hard sometimes, many of these fish just barely hit an actual aquarium and many will need live foods to think about eating and then will need to be weaned. It's pretty difficult.
So if you have the experience and equipment to handle a box or more of fresh imports and are able to find a place that has a fair price then the choice is up to you, but overall it's a lot more difficult than regular online orders.