I feel like I wouldn't trust the devs there, unless i can verify/get to know them physically outside it would feel like throwing money in the wind and hoping it works
Anyone that tells you they can take your random idea and implement something high-quality and useful (if that's even possible for your random idea) for 400€ is indeed not to be trusted. The kind of skilled, competent and trustworthy people you're looking for would know that it's a recipe for disaster.
(400€ is USD$450. At an already low $50/hour, that's 9 hours. Or at a ridiculously exploitive wage, when it comes to software devs, of $25/hour, that's 18 hours, or 2-3 solid days of work.)
Actually I met a guy that made easy money with one of these freelance sites where he was very reputable. I didn't understand it until I looked carefully at his responses to offers.
The key was that he had an extraordinary skill to translate the offer from ignorant, unrealistic, ludicrous, I-want-the-Moon expectations to a practical setup where the real work was to install an OSS PHP forum, apply some stock themes and program a couple of pages of functionality that wasn't out of the box.
He dressed this setup as matching, even exceeding expectations, and delivered ultra fast.
Do you think the customers were deceived? On the contrary, they were delighted and with reason.
The problem is that customers have little knowledge of how to describe their ideas, that they're (of course) in love with, and tend to present their requirements in a hyperbolic language so they seem to be asking for "a Facebook" for a hundred dollars.
I used to get paid 500€ a month as a developer for a consulting firm, and it was a 12-hours-a-day kind of a job. The firm would then bill its clients 40-60$ for every hour I worked. From one perspective it does seem exploitative. But on the other hand, I know many people who still dream of getting that job - the money is not good, but it almost doubles when you get promoted, and the career path is good. It's a really intense place with almost impossible deadlines, and you get to learn a lot from the pressure.
I was recently offered a project where I had take a complex analytics algorithm implemented in Excel to the server and implement it as an API for ~250-300$. Took me around ~20-30 hours over an extended weekend to write it in golang and I feel good about it. The work was mostly simple transformations on the input data, though a large number of them. It resulted in roughly 1000 lines of code including tests and comments, and a big part of that time was spent actually understanding the algorithm.
Similarly, I did some work as a favor to a friend - a Facebook app that would send some inspiring quotes as notifications to it's users every few days. It took me maybe 10-20 hours to get it online. Frankly, I am not so proud of the code as it was written in such a hurry, and is a bit messed up. But to its merit, it's been functional for several months without any noticeable downtime, and has sent thousands of notifications so far without any need to touch the server.
These are the kinds of projects that can be done in a short amount of time without a long-term commitment, and make sense for such a budget. For me atleast, 10$ an hour is good money, and 25$ would be pretty decent. 50$ would be something of a dream - I would be making in a day what I used to make in a month at my previous job.
Okay, so 1/3rd of the monthly wage means 1/3rd of a month, meaning 26 hours of 4*40 hour weeks.
Assuming there's no other overhead an independent contractor needs to take care of in Italy (in the US the big one would be health insurance, but you live in a civilized country. On the other hand, your civilized country probably all takes reasonable paid vacation, and an independent contractor would probably want to charge enough to do the same. And there are other reasonable reasons contractor hourly rates tend to be higher than pro-rated full-time salaries, things included with a typical full-time job above the salary itself that a contractor has to pay for or spend time on themselves).
But okay, let's say 26 hours.
How many junior developers can take an idea, probably somewhat vague and poorly thought out, and turn it into something useful in 26 hours?
I'd say if they can, they probably ought not to be considered a 'junior' developer!
I meant it as 26 hours total, but I had my math completely wrong. 40 hours a week * 4 weeks * 1/3rd is 52.8. I had it halfed somehow. But anyway, yeah.
It's 1/3rd the net monthly wage, i.e. probably less than 1/6th of the money you pay to have junior developer actually working for you for one month, once you factor in income tax, company tax, social insurance, sick time, vacation time and national holidays.
I wouldn't expect a junior to be able to manage the whole stack and get stuff on a server. Write an application probably, but it took me a few years before I could manage everything.
I feel like I wouldn't trust the devs there, unless i can verify/get to know them physically outside it would feel like throwing money in the wind and hoping it works