With your machine, I would recommend the Whirl-A-Way 18". I prefer the model with the wheels. I have had mine about a year and I use it almost everyday for drives/walks. Just remember...the grease fittings are there to be greased!
I believe the Whirl-A-Way comes with 25* tips, but with 3000 psi, you may need/want to go smaller...that would be a good question to ask. I have seen this model advertised for anywhere from $429 to $599. As service should not be an issue, I would buy it from the least expensive. As I remember, Northern has it for $499.
Hope that helps...and I hope you were asking about a surface cleaner! lol