What is the cheapest plan to receive SMS's

Hi all,

I'm on an amaysim plan that's expired (was one of those 6x 1month for $10 Groupon things) and all I use this number for 99% of the time is receiving SMS verification codes for the business. Occasionally I receive incoming phone calls, but I have another number (business land-line number) that we make calls from.

I'd like to keep the number for SMS verifications and am looking for the cheapest pre-paid or plan based account that can do that for me. Ideally I'll never call or SMS anyone from this number - so the cheaper the better. Also don't need data as I have another SIM that already gives me 80GB data per month.

Thanks!

Edit: For what it's worth I think ALDImobile for $5 will do what I want it to do - but can someone confirm that if I just get a $5 pre-paid kit I can port my number to it from amaysim and then use it for the next 365 days to receive SMS's without worrying?