Right, didn't think of that. I have a $10/mth 1GB roaming plan that I use regularly.
1st time simcard purchase (digi telco) - rm20 (has talktime and data as well already).
Subsequent top up every time I enter in JB cost me rm10, out of which - rm4 will be deducted for 500mb data (which I had choose to subscribe to during my 1st time simcard purchase) while the remaining rm6 is for call/sms.
And digi has a long prevailing promo - spend minimum rm1 and redeem free 200mb data.
That effectively makes it 700mb worth of data for a same day return trip for only rm10.
Topping up rm10 will activate the simcard for 10days, so if your next visit is more than 10 days later, just top up rm10 again to activate simcard.
If you are traveling into jb again within the next 10 days, don't have to top up and just use the 500+200mb data and whatever value left in it for call/sms.
Lastly, even though it gets deactivated after every 10 days (different top up value will determine the activation duration) the previous value doesn't expire and will stack onto the new top up value.
All these info will be sent via sms to you the moment you make a top up.