'wget' just transfers the file, AFIK, it can't be used to assist in an import. If you mean you are exporting the data, then transferring with wget, here's what I'd suggest.
When you save the inventory from the online store, what format is it stored in? If you have the ability to choose, choose 'CSV'. If you are using Excel, you can just 'import' and tell Excel that it is CSV. You'll also have the option of choosing other delimiters and specifying data types (e.g., date). Very easy.
If you are using an 'official' export function in a online store, it almost has to support CSV.
If not, then you'll have to figure out what delimiter (if any) is being used and try to coerce Excel into understanding that format. Some primitive systems might not use CSV, but rather fixed-length fields (e.g, 'id' is in columns 0-9, 'description' is in 10-40, etc.). IIRC, you can also specify fixed length fields in an Excel import.
Worst case, which is extremely unlikely, you'll need to write a 'filter' to convert the format used by the store to another format supported by your spreadsheet, most likely CSV.
--Ma