PAYG Roaming to USA - Data bundle pricing

[JKCR]

I am travelling to the USA and cannot find out what the pricing is for data while there. 

I am a PAYG user from the UK, travelling to the USA.  

Looking it's clear what the roaming charges are for everything bar data. It's just saying: 

Data/internet:

Buy data add-on when you land

But there is no indication to how much these cost or what form those data add ons are. 

I have asked customer support but they say they cannot tell me the price or shape of these bundles. I have to wait until I land to find out what is on offer. Naturally I am worried that the cost of data will be extremely high.  

Does anyone know or can anyone give me an indication of the data bundles offered when you land, either the per MB or the bundles and cost. (e.g. 1GB = £10. 5GB = £20 etc.) 

[XRaySpeX · Accepted solution]

I believe they the Zone A Roaming Data add-ons outside of EU/EEA/Switzerland countries (Inc. VAT) shown on p12 of PLAN PRICE GUIDE Non-Standard Charges Pay as you go 

[JKCR]

For those who don't want to click at the time of writing it's £5 for 50mb. £10 for 150mb.

I decided to get an Esim through Airalo, simple to add and got 5gb for $20.