If I was going to spend $500 on eyepieces I'd rather get the ES 6.7mm ($100), 18mm ($149) and pick up a 2x televue barlow ($129), or a similar pair of sizes (say an 4.7mm and a 14mm and the barlow)
http://www.explorescientific.com/eye...ee_series.html
http://www.bintel.com.au/Eyepieces-a...8/catmenu.aspx
You will have spent <$400 and will have eyepieces that may well last you a lifetime.
The ES eyepieces are brilliant, 82 degree field of view, waterproof, wont fog and you will effectively end up with 3.4mm, 6.7mm, 9mm, 18mm eyepieces by using the barlow. Or pick a pair of sizes that suit your viewing habits better. You won't outgrow these eyepieces even if you upgrade your scope, and the 82 degree view is way more encompassing than the 52 degree field in the kit eyepieces.
You won't really use the coloured filters at all in my experience.