Ask HN: How to determine company valuation?

We are a technology start up in photography domain based out of Europe. Our target customer segment are professional and semi professional photographers.

The team comprises of the CEO (Senior Executive with more than 15 years experience in Sales/Marketing) and 3 Software Developers with 3-4 years experience.

We launched two months back and have got good response. (However, we are not profitable yet). The seed investment into the company is close to 100K USD and we are trying to raise more funds now.

I was hoping to get an idea on different ways in which the valuation of a company can be calculated especially the ones that are in the stage as ours.