When I see a new, usually younger, member join, I often see a post such as "How do I buy diapers?" or "I'm living with my parent(s) and can't get any diapers." I, like many of us, were in the same boat. I have offered suggestions and will republish them here and hope others will share their experience as well.
If you don't have transportation, you are definitely limited. If work is not available where you live, such as baby sitting (PLEASE don't steal diapers. You will probably get caught) or mowing lawns, then perhaps you can make your own out of old towels and back it up with plastic trash bags and tape. I actually read where someone did this and thought it was very creative. Also, if you Google "Home Made Diapers" you will get some information there as well. Try not to use Mom's favorite designer towels, or you will have hell to pay. Also, you need to do your own laundry with this idea.
If you have money but no transportation, the next time you're at a store with family or friends, sneak off to "look at something else" and buy a pre-paid Visa or MasterCard. Then you can order diapers online. Warning that some of those cards have expiration dates. The store gift cards such as Wal-Mart, Target and Walgreen's do not have expiration dates or fees.
The problem with ordering online that I hear most often is "What if someone see the package?" That is a problem if you have parents in your business. With transportation, you can have them delivered to a shipper facility such as UPS or FedEx. The "stores" with these names will charge a fee, the warehouse pickup sites will not. With no transportation then you either have to be there when the package comes, which you can track online. Or, ask a friend if you can have it delivered to his/her house and if they don't know your secret, tell them it's a surprise present for your parents. Then you have to sneak the box in when they're not home (use a backpack if you can't get the box in all at once).
Another idea is to walk around your neighborhood (if it's safe) and look for what we call in the US as "garage sales". A toddler may have suddenly become potty trained and the parents will have no use for some larger diapers. You can usually barter with them and get the price down. Make sure it isn't someone you know and use a story like it's for a friend's niece, or something.
If you have money and transportation, the possibilities are almost endless. If money is limited, then try the dollar or discount stores. They are affordable, but remember, you get what you pay for. If money is no problem, then you have the options of going almost anywhere to buy. If you live in a small town, try another town nearby so no one recognizes you. Even still, you might want to buy somewhere out of your neighborhood or at least a larger store where the employees aren't likely to know you.
All of the options above for the no money/transportation ideas will work for you as well. You have the added option of driving to the UPS or FedEx store to pick up your stash. Also, Wal-Mart and Target allow free delivery and pick up at the store for products bought on their website.
One more thing. I don't know about other countries, but here in the US we have so called "Big Box" stores like Sam's Club and Costco. If you can get into these places either with your own membership or someone else's, it's a huge deal as they have big boxes of diapers for not much more than you would pay for a smaller box at the retail stores. They usually have Pampers, Good Nights and Huggies as well as adult brands such as Depends and their own brand.
I think that sums up my advice and ideas. Anyone else have some ideas for the "diaper impaired"?