That's an easy one, you say "no." While I am sympathetic to cash preservation and bootstrapping in the early days, we have no obligation to provide free or even discounted work to anyone. Startups can develop their own site or if they consider it a priority find a service within their budget to make it work. This is not being mean or selfish but a good steward of your own business. You have to take care of your business too. Every startup believes in their business but truthfully not all make it. It's not fair to offer equity unless independent of the ask you would have invested in the business, for your time and services. Tell them no, and offer to provide a quote when they have the budget and don't feel guilty. We all have a limited supply of funds and time and have to make tough decisions about how to spend them.