Python 3+ help needed: search for multiple RegEx substrings

Python 3+ help needed: search for multiple RegEx substrings

It may be newbe question, but I'm stuck:
I've got a SQLite table with sells records - where in field 13 located
shipping prices - there are essentially 3 possibilities:

Price: for ex. £15.20
free
not specified

Problem is there is not always only these words: for ex. it can say
"shipping is £15.20" or "shipping free" - I need to normalize it to the
aforementioned possibilities. I use RegEx:
def correct_shipping(db_data):
pattern=re.compile("\£(\d+.\d+)") #search for price
pattern_free=re.compile("free") #search for free shipping
pattern_not=re.compile("not specified") #search for shipping not specified
for every_line in db_data:
try:
found=pattern.search(every_line[13].replace(',','')).group(1)
except:
try:
found=pattern_free.search(every_line[13]).group()
except:
found=pattern_not.search(every_line[13]).group()
if found:
query="UPDATE MAINTABLE SET Shipping='"+found+"' WHERE
Id="+str(every_line[0])
db_cursor.execute(query)
db_connection.commit()
But this code is raising exception
AttributeError: 'NoneType' object has no attribute 'group'
- first result in form "5.20" trigger it because none of patterns is found.
Question is how to properly search for string (is try/except is necessary
at all ?) or how just ignore exception if none of the strings is found
(this is not so good solution though ?)

Thank You in advance