From the standpoint of a full PC-Gamer, Shop cards at $7 for 30 days is not much to ask for considering the cost of PC gaming.
If you are a adult who lives in your own home and takes care of all the bills, the following are your costs associated with PC gaming:
~Building your PC
~Setting up your area for your PC. (A desk, chair, setting a room aside for this)
~Cable Management (Don't Laugh... this is a thing that can cost hundreds, specially if you live with children)
~PC Monitor (or TV)
~Sound System (Speakers, Headsets, Mics, etc)
~Monthly Electric Bills
~Room Maintenance and Cleaning (where your comp is)
~Internet Connection (monthly bills and any security software)
~Operating Systems (if you pay for them)
~Keyboards, Mice, and Peripherals
~Buying games in general along with their DLCs (or in the case of F2Ps, blowing a lot of bandwidth to download on metered connections)
When presented with all of these costs, $7 is not asking for much.
My argument is the duration of these cards.
I would much rather buy a pack of ten 3-Day Shop Cards as opposed to a 30 Day Shop card.
30 Day Shop cards force players to be very aggressive to maximize them.
I have the same thought with premium.
I'd rather have three 10 day premium passes as opposed to a 30 day premium subscription considering that life gets busy at certain times of the year and it becomes harder to commit to a duration of 30 days considering everything else that takes priority in order to pay the bills, live a healthy life, and maintain relationships.
Not even a job forces you to commit to 30 consecutive days of work in this day and age.
I wish these passes were more aligned with average lifestyles.