I never experienced this, but I did wait too long to buy a domain. After I checked if the domain was available(it was), I started building the website. A month later the domain was bought by someone who eventually made the same thing I wanted to make.
My current process for checking if a domain is available is pretty basic. I first check it in the browser. If Firefox can't find it, then I use the `whois` command. If there is no match for "example.com" then I decide if I want to buy it, before starting to build anything. If I do decide to get it, I go to Hover.com do a final check and press "Add to cart".
These days, for me it's better to spend $15 on a domain that might not get used, than to regret not buying it.