I had a similar experience with naive price expectations. I obtained 10 quotes (often had to ask follow-up questions, appointments were quick, I am still waiting for some quotes today). They vary a lot. Paving 150m² at €23/m² gross for paving stones. About 20-30cm gravel base, fine gravel, laying, 46m edging stones, cutting the pavers. Everything from €12,000 to €18,000 was quoted. The normal price is therefore about €10/m² including stones. When obtaining quotes, also consider up to 50km distance. The more rural, the higher the chance of a cheaper offer in my experience. Also, you could post your job on a craftsman portal (e.g., MyHammer) and wait for offers.