Having your own domain and hosting is not as pricey as time you will invest in any project presented on the site. If you take it seriously, make your commitment to the project and buy yourself a domain and hosting or host your blog elsewhere - if you are gonna make your audience, then you can get a blog at medium dot com which is quite popular and you do not have to play around.
Domain is a long term investment and as long as you do not spend a fortune on it, go for it. After all, it is not a huge amount of money. Domain is also about branding yourself, which increases added value of services provided to your current and potential followers.
A friend of mine made a stunning presentation for his consulting business just on tumblr and for free so yes it is possible to make it for free if you have skills. If not, be prepared to pay. Websites made by cheap sellers like for $50 are worthy $50 or less. How much worthy is your project you are about to launch?
I can say that creating actually a website working for your business ( and there are too many sites which actually ruin it ) and increasing perceived value of your company will cost you at least few hundreds US dollars in developed countries.
Just a small sample breakdown of small WordPress powered site made somewhat at industry standard:
- $50 for professional theme license
- $50 for optionable custom plugins you may need
- $50 for photos you can not get in CC0 licence but you need them to get some visual sexappeal
- about 8 hours to setup the layout, design and input few pages of content, basic SEO, security...
It pops up very quickly.
DISCLAIMER: Provided prices are very careful and you can be presented with below industry standard prices as well as dumping prices for your project. Always take care of quality - if your site does have leaks and issues, you can loose your customers, which is more expensive than a good website in long term.