A few weeks ago an inventor told me that he was checking into the cost of manufacturing before having his patent search reviewed. This was a bit out of order but not a huge issue. You want to understand the costs involved before jumping off the cliff.
However, I found out later that the inventor had gone ahead with a rather large order before having the search reviewed and patent done. This is not a fatal inventing mistake but it can certainly be an expensive one.
There can be several problems with manufacturing first. They are:
If you are going to bet your financial future on a new idea, it is in your best interest to do it right. Make sure you do your homework beforehand.