Note that I've found almost all my projects since 2010 on CraigsList computer gigs in various US cities. That makes for some eclectic, shall we say, people. Why I hunt on CraigsList is another topic.
Even for relatively small projects, a quote would take many hours to produce, so I can't afford (at this time) to give free quotes. Anyone who can afford a free quote is going to give you a large one--perhaps many times more than I would wind up doing it for. As for why it takes so long: for one, I almost always have to ask you lots of questions. Even well-written ads that demand quotes are almost never complete enough to even think about quoting, so I still have to ask lots of questions. Also, the response rate to CL ads is low. I won't consider quoting until I know you're real, and we have a path of communication.
If I did quote, I'd have to estimate way high. If you demand a quote, I have no sympathy for you if my hour count was actually a vast underestimate. That is, I'll happily take much more money than I would have if we had done things differently. A quote is an enormous risk, and one of us is probably going to pay for taking that risk.
My project management course professor worked for HP and Lucent. She told us that estimating is extremely difficult, a black art. She said that you had to relentlessly try to take into account all the factors. Then, when you think you're all done, double it.
Building software is not building a house. The variables involved in a house are trivially limited versus software. A builder can build dozens of houses and get better and better at estimating. Of the few dozen software projects I've done, they aren't similar enough to each other. Also, given how vast the technical field is, every project likely involves something new, and I have no way of knowing how long that learning curve will be. All I can do is give you ranges of how long various learning curves took in the past.