I just want to emphasize how important it is not to use UPS or FedEx.
UPS is the worse of the two, but FedEx is gaining ground fast. UPS will charge you a minimum $38 "brokerage fee" just for bringing your package across the border. Any duty or taxes are on top of that. They charge at least $38 regardless of the value of the item. It can go up from there, though.
The most extreme example of their thievery I have heard is with a friend who got a magazine arrive without the free CD it was supposed to include. He called the company and they were gracious and sent him a replacement CD. Unfortunately they used UPS. Naturally, they wanted $38 for the CD, even though there was no tax, duty or other fees owing. He didn't want to pay, but they told him they would refer it to a collection agency if he didn't.
I've been burned several times by UPS. When I buy something from the US I always explicitly request that the item be sent by USPS. A couple of months ago, a seller used UPS anyway, despite our agreement. My $63 dollar camera accessory ended up costing me well over $100. It would have been much cheaper to have bought it here.
This week, FedEx sent me a bill for a pair of headphones that were delivered a month and a half ago. The headphones were $40, but the seller had insured them for $100 for some reason. The driver didn't ask for any money when he delivered the headphones, but more than six weeks later I got a bill for $42.17 for brokerage fees, a "disbursement fee" which is apparently a fee they charge you for collecting your money, as well as GST on both of these "services". There was also $6 worth of GST on the headphones themselves. At least they didn't charge me GST on the GST.
So, my $40 headphones, with the original shipping costs and the additional added fees, ended costing over $100, more than $60 of which went to the thieving bastards at FedEx. Again, the threat of a collection agency and credit rating ruination left me paying the fee just to avoid the hassle and get rid of them.
I've come to the conclusion that it really isn't worth buying things from the US, whether it's through eBay or from a regular retailer. The big courier companies have a racket going that should be illegal. There are some class action lawsuits underway in BC, but I'm not aware of anything in Ontario yet.
USPS is the best way to have something shipped up here. There is sometimes a $5 borkerage fee from Canada Post, but it only seems to happen about one out of three or four times. I'm not sure what their criteria are. It may happen or it may not.
In the end, though, you're probably wise to just find a set of 595s in Canada. In the end they'll be a lot cheaper.