I've never seen this and have no idea what price would be expected of it, but, at first glance, this seems a good price. Can't find at Buy or DDD, so no idea what I should expect.
That's a great price for the whole series. Bought this last December from Amazon for $10 more. If your a fan of the series, this is definitely a great deal and if your not, it's not a bad deal at ~$11 per season.
Managed to hold off on buying when it was $65 a few months ago, but can....no....longer...resist, even though I already have season 5. Too good to pass up at that price.
Thanks OP, although I am also cursing you for getting me to spend another $50+ on DVDs.