I'd like to import CSV file into Salesforce automatically, e.g. once a day. I can't use Data Loader (Bulk API), because I don't have the needed edition. Is there any other, simple way?
you can use Salesforce import wizard. If it is an Standard object you can use directly Import Account/Contact, Import leads, Import Opportunities etc.
You can also use jitterbit dataloader which is available for group edition, Belo it the link for same
Or you can enable bulk api then you can use apex data loader.