For my Canadian sister I needed a different solution. She has no net connection, no computer, and no wifi. She's off the net and her budget is limited. For her I wanted enough data to do basic email, iMessage, and non-video Facebook and emergency voice services. I had an unlocked refurbished AT&T iPhone 4, and I had some experience with Virgin Mobile Canada prepaid data - I decided to try that combination aiming for a cost of about $200 a year (not including the phone).
So far it's working, but Virgin Mobile is no Ting, it's not even AT&T. Be warned; I'm not at all sure this is a good solution.
I followed the general procedure I documented a year ago for my own personal use (if you're in Canada you can order SIMs for 0$ from Virgin, I paid $10 at Future Shop). Once again Virgin's web site didn't recognize the AT&T iPhone's IMEI. The web experience was painful -- I was almost done when I timed out and had to restart (moving more quickly). This time around I paid more attention to how much spam Virgin generates -- their contract authorizes an appalling amount of spam (email, sms) and telemarketing/robocalls to any email or phone number you give Virgin. Follow the link to track all the places you have to go AFTER you sign up. See also turning off Virgin's text spam and email spam. To turn off the robocalls you need to call from the mobile phone at 40cents/min; when I did that I found the number was already DNC but I extended protection for 5 years.
Just like last time it took about 30 minutes to activate my sister's account on the web site. Until the account was active entering the number created a password prompt, only after activation did I get a PIN prompt; with prepay you don't get an honest password and username, just a phone number and PIN. It took another 30 minutes to activate the phone.
Then I ran into a bug I'm still sorting out. When I tried to use my balance to purchase the monthly data add-on I got "...Contact our Customer Care at 1 888 999 2321 so we can help." I was able to use Chat to complete an initial purchase and make a change to to the recurring purchase, but when I asked why I couldn't do it online I was told there was a "web site problem". I later found that this is what the call center operators are told to say.
It's not clear what the problem is. As I noted above, Virgin didn't recognize the the AT&T iPhone4's IMEI; maybe the website can't tell if I should see the BlackBerry or Smartphone options. Or maybe there's some weird rule here I don't understand yet. I'm slowly working this with tech support
Between Chat Support and the web site I've put together some notes on how Virgin does prepaid plans and prepaid data as of March 2014: 
- $15 Top Ups expire in 30 days, $25 and $50 Top Ups expire in 60 days and $100 Top Ups have an expiration period of 365 days. (A Top Up is simply a credit one buys from Future Shop and other retailers.)
- Unused funds expire at the end of the Active Period unless you Top Up within 7 calendar days of their expiry. If you Top Up before hitting zero the new Active Period will apply to the combined amount of prepaid funds.
- Expiration is based on the expiration date of the latest Top Up. So if your credit expires in 60 days, and you buy a $100 Top Up, expiration is 365 days, not 425. Other prepaid vendors are much better; the expiration date is sum of original remaining plus new. (If expiration is 365 days and you but a $10 Top Up what happens then? Nothing good I fear.)
- If you run through your Data Plan, Virgin charges per MB overage fees until your prepaid balance is exhausted. (If you optionally associated a credit card with the prepaid plan I suspect the credit card is charged until your bank account is exhausted. I don't know if this applies to INTERAC purchases.)
- If your prepaid funds expire and you do not top up for 3 months your account will completely disconnect. (It may be possible to 'reactivate', but I don't know how that works or for how long.)
- 10$: 100MB
- 7$: 500 text
- 3$: minimal voice