More than a long piece of string? Of course it depends.
Here is our ready reckoner (the interactive chart is indicative as every job has unique requirements, but allows you to compare OL with a commercial option):
Basically the more you expect from your website, the wider the range of features, the better the design, the more complexity you build in the more it will cost you.
Of course you can do it all for FREE on ourlocality, and some other DIY systems are seriously powerful too, but do you have all the knowhow and indeed the time?
We know a few people with the former, but absolutely no one with the latter – even in a recession! If you need autonomy and total control, the self hosted is probably the only option – we’d be happy to advise.