Is there anything I can do after served with a summons for divorce?

California Courts have a "fee waiver" process wherein you file certain documents and request, based on income, that the filing fees be waived. Check online and determine whether there is a similar process in Colorado. Divorces do not need to be contentious or nasty, it is really about splitting up what assets and/or debts you have, and determining the best timeshare for children (if applicable). If you and your wife can come to an agreement on those issues, then you can just file your agreement with the court.

You should respond. Maybe you qualify for a fee waiver. At least go to the courthouse to see what help is available or buy a book on doing your own divorce. If you can't borrow money to hire an attorney you will have to represent yourself and learn how to get through the process.

This is more a question for a Colorado attorney, to wit, is there a fee waiver program there [as there is in cali] which would allow you to file a response without paying a fee on the grounds of economic hardship?

The bad news is, if your wife wants a divorce, there is little you can do about it. Your consent is not necessary. The good news is, both California and Colorado waive court filing fees for parties who meet low income criteria. You should apply for a fee waiver and file a timely Response to preserve your rights. If you fail to do this, the Court may proceed without you and serious legal consequences could result.