Yea I always just assumed the kanji would be 毎度, so I had a good idea of what it meant. It's like "いつもお世話なってます".

So it is something they say when you enter a shop then? I'm pretty sure I heard it in a cafe in Osaka and at a weird back alley (pillows and things) type shop in Tokushima. Other than that, I don't recall hearing it when entering a shop. (although I've heard it used in other situations).

I wonder if there are other words used for irashaimase in other dialects?

Dialects a side, there are about a million different ways of saying "irashaimase!".

There is a っ in there: いらっしゃいませ.

I am pretty sure that some of the comments made here are confising the OP more than helping him/her.

Just read the original question again!