Pay as you go broadband

I am looking into this for my mother.
She currently uses dial up, which is painfully slow.

She does not want to spend a fortune every month on this, only pay per use.
She does not spend hours on the internet, just emails and a bit of surfing.

She would be likely to use it most days, maybe for 30 mins or an hour.

I am looking at the various choices and they seem to work out pretty expensive.
And you also have to pay per 24-hour day rather than per use, which is not suitable for her.
Are there any choices that I may not be considering?
Speed is not an issue, but 512MB would be the minimum I would like her to have.
Download limit not really an issue - she would not be downloading large files.
Set up cost not really a factor - I would be willing to purchase any hardware myself for her.
Paying per minute or MB would be best.

I recently signed up for Vodafone mobile BB. Not pay as you go obviously but it's only €20 per month - no other costs, dongle is free.

She might find she is paying close to €20 per month on dial up anyway - unless she's downloading a load of movies she'll never reach the monthly limit Vodafone limit. Plus obviously, much faster and you can use as often as you like.

Had 3Pay and they would charge for a period of time. You bought 1 weeks, you only had one week from the time you activate it to use. Same with Day/Month.

Not sure there is a credit system as per mobile pre pay for broadband.

Looking at mobile broadband options. I have Eircom broadband at home but I need access at a property that I'm doing up.

O2 and Vodafone reception is good there. I don't want to install a landline as it wouldn't be cost effective. Some kind of broadband-pay-as-you-go would be ideal.

Recommendations appreciated.

Got the Vodafone dongle last month and stuck €20 on it - good (enough, most of the time) coverage, just wanted it for booking things, surfing, uploading pictures up to Photobox etc...and have found it really good.

We haven't yet used quite half of our (5mb??) allocation , though you can't carry it over - the 2.5mb odd we have left dies with our month end on Sunday. I was wary of overusing it, so have been monitoring it closely - next month for example, I'll probably surf YouTube more, now that I'm more aware of my usage.
If you know someone who uses a mobile datapack, get them to surf a bit in the house if at all possible - if the (Vodafone/O2) network is ok on their phone, it'll likely be similar through a dongle.

We used it as a trial run on wheteher we'd add broadband to our TV pack - we won't - for the 1hr we use it a night, the €20pm is perfect. Plus you have the added bonus of taking it with you on the move (I had an hour to kill in a parked car recently - RTE Player is your friend!!).