Hey Backdoor man, and welcome to the forums :)
Just from first glance, I'd say that the Hearts of Love Suction Butt Plug probably isn't the best toy to choose for a beginner - dimensions-wise that might be throwing her in the deep end, and I don't know how ideal ridged design toys are for first timers. Perhaps you should settle for a basic/ simple butt plug to start off with, and work up to this?
The Tracey Cox Beginners Kit is specifically designed for such a user, and has been rated pretty highly by quite a few users on this site. (http://www.lovehoney.co.uk/product.cfm?p=9758)
If you wanted to get something considerably cheaper, possibly My First Anal Experience Small Butt Plug would be worth trying (although it hasn't been given the best write up). (http://www.lovehoney.co.uk/product.cfm?p=6971)
The Basix Mini plug is going for the same price (£4.99), but the lone reviewer has very positive things to say about it (coming from a beginner too). (http://www.lovehoney.co.uk/product.cfm?p=13990)
But a multi-pack of different sized toys may be the best idea if you do really like the look of this Hearts of Love plug - build up to that size gradually.
Backdoor man wrote:
My girl is a beginner in anal, though she likes to stick there small vibrator.
Is this a vibrator that's for sale on LoveHoney? On all of the product pages here, you can find a small section under the product description; How it measures up. I'd recommend comparing the circumference measurements on both of the toys, and this should give you an idea of the differences between them.
Best of luck in finding the right toy though!