Biztalk overkill

I get a lot of flat files from different formats, which i need to add into database.

For that i was recommended by someone to use Biztalk.
I tried it and made multiple applications for different file formats, I made schema and then added .NET code to add that data in database.  This all worked fine, I had 1 development server which i was using to update database.
Now clients are asking me to give them the application from which they can do the migration themselves.
But Biztalk editions are quite costly and also on further research i found that for such tasks which i am doing, It is over kill to use Biztalk

I want to leave Biztalk now and use some Other application or Library which could convert the flat files to xml and give to my application and then i can use the same code and put data into database.

Please recommend some other library or application which could convert the flat files of different formats using delimeter approach or fixed length approach to xml, which are cheeper or free.