T-SQL Search In String for specific words - string

Question

Short to the point:
"I am using SQL Server Manager 2008 R2. I have a table with columns "product name" and "product size". The size of the product is recorded in his name like that:
Ellas Kitchen Apple & Ginger Baby Cookies 120g
Ellas Kitchen Apple, Raisin 'n' Cinnamon Bakey Bakies 4 x 12g
Elastoplast Spray Plaster 32.5ml
Ellas Kitchen Stage 1 Butternut Squash Each
the size of this product should be:
120g
4 x 12g
32.5ml
N/A
(some of the products can have no size in there name and should be set to "N/A")
I want to write T-SQL statement that update the product size getting it from the product name.
I have done this in javascript, but in order to do the things right I have to write SQL statement and that's my problem. I have found it very difficult to work with "regular expressions" in T-SQL.
I have seen a exmaple of how to get only the number from string, but have no idea how to do using sql.
Declare #ProductName varchar(100)
Select #ProductName= 'dsadadsad15234Nudsadadmbers'
Select #ProductName= SubString(#ProductName,PATINDEX('% [0-9]%',#ProductName),Len(#ProductName))
Select #ProductName= SubString(#ProductName,0,PATINDEX('%[^0-9]%',#ProductName))
Select #ProductName
I will appreciate any example or idea.
Thanks, in advance.
EDIT:
Thanks for your reply,xQbert.
I have not included all possible formats, because if I have a working example with few of them I think I will be able to do for all. Anyway, in order to give more details here are the possible situations:
( Inumber + "x" + Dnumber + word)* + (_)* + (Dnumber + word)*
- * means 0 or more
where word can be - g, kg, ml, cl, pack
where Inumber is integer
where Dnumber is double
where _ is space
For exmaple:
12 x 100g
100ml
2 x kg
And the price (if there is ) is always in the end of the name:
Product name + product prize
For example:
Organix Organic Chick Pea & Red Pepper Lasagne 190g
Organix Organic Vegetable & Pork Risotto 250g
Organix Rice Cakes apple 50g
Organix Rusks 7m+ 6 Pack
Organix Savoury Biscuits Cheese & Onion Each
Organix Savoury Biscuits Tomato & Basil Each
Organix Stage 1 Squash & Chicken 2 x 120g

Answer 1

PATINDEX is not REGX and you have limited logic processing in TSQL compared to .NET. Have you condisidered CLR integration?
http://msdn.microsoft.com/en-us/library/ms131089(SQL.100).aspx
This from 2005 but and example of REGX in SQL via CLR integration.
http://msdn.microsoft.com/en-us/library/ms345136(v=SQL.90).aspx