Business sale costs

I'd have a look on the tax returns from the last 5 years, age and shape of inventory, talk to the suppliers and customers.

Owning a business doesn't mean you can run it. All permits and licenses are on the avtual owner an cannot be transferred (except in case of a corporate entity). some activities are subject to special permits and autorizations.

I haven't seen the 3x valuation used in the real world for 20plus years. Even then it was only used to calc the "goodwill" for the business, on top of that went the assets. 

There really isn't any simple formula to value a business as there are way too many variables. 

I last sold a (thriving) business two years ago, the figure we agreed on had no relation to the net profit, it was just a number they could afford and I was happy to walk away with. I'd suggest this is the way most businesses that are talked about by people on forums like this (ie. not national or global conglomerates) are valued.

If you are looking to buy a business in Spain right now, or anywhere really, I'd say you hold all the negotiating cards, so bargain hard. If selling, expect to take a bath!

In terms of the business existing profit... Whatever it was, assume it's now zero going forward. Use that for the basis of your valuation.

Whatever price you agree, if buying, ensure you do "due diligence" taking legal advice from a source you know and trust, not suggested by the other party.

Personally if I were looking to buy any business anywhere right now I'd base what I'm willing to pay on the assets only, with a chunky discount. It's a buyers market with everything right now and that isn't going to change anytime soon.