Javascript - Validation Using AJAX Without Update Panels

I'm looking for a way to use custom ASP.NET validators to validate input, without using UpdatePanels, and without a full postback. The validators do several things - not just length/regex, but some other non-standard stuff as well. Javascript is required for our users, so I don't have to worry about normal users who have javascript turned off. I see several options, but none are ideal:

1) Suck it up and use UpdatePanels. I'm in the "UpdatePanels are evil" group, so I'd prefer not to do this.

2) Without using validation controls, manually validate the fields by passing the values to a PageMethod static method, via jQuery or any other AJAX framework. This would require client and server coding each time I needed to use a validator.

3) Use jQuery (or any other javascript framework) validation for client validation, then if they somehow get by that, have server-code validation controls for full postback. This would require all of the validation rules to be written in javascript as well as C#. I don't care about the full failed postback at this point, because the javascript validation would catch real users who weren't trying to screw me over.

Is there alternative out there for using real CustomValidator controls, with partial postback, C# code only, for validating input without UpdatePanels and without a lot of redundant javascript?