You are pretty much on the right track...And its good that you have picked out areas/categories that interests you. It's usually easier to pursue something if it is something that you have interest in.
It's true that it may cost you a little extra (or maybe more) trying out these suppliers, but then again it's not that bad an idea. Ideally, I would suggest this as well. It's best to test the waters before taking the plunge. So you could make test/sample orders to see the quality of the products as well as the reliability of the suppliers.
But you have to take in consideration that even though it states that 'shipping will take between 4-5 days' there may be external factors that can cause the shipping to be longer than stated.
Here's a thread that has a handful of tips you may find helpful, please have a read:
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Here are some simple things you can do to protect yourself when dealing with any supplier (especially those found outside of SaleHoo).
1. Run a whois check on the supplier's website to verify when it was created (it is safest to deal with suppliers who have been online at least 2 year), who owns the domain, and where the domain was registered (the country should match the contact details on the supplier's website).
2. Search the SaleHoo forum for the supplier's website/company name and see what other members have to say.
3. Call the supplier's telephone numbers to ensure they are genuine.
4. Purchase a sample before bulk ordering to ensure that the item meets your expectations. (You've already thought of this!)
5. Watch out for sellers asking you to 'safeguard' your purchase by sending your money transfer in the name of a friend or loved one, or by establishing a 'test question'. These actions will not protect you from a fraudulent seller.
6. Low prices do not necessarily mean fraud, but radically low prices should warrant a closer look. If a price seems to good to be true, it probably is. Ask the seller as many questions about the item's authenticity as you can before you go any further.
7. Always use a credit card or Paypal to purchase goods. These forms of payment are safe because they give you a comeback if something goes wrong. With these payment methods, you can usually have the transaction reversed fairly easily if necessary.
All the best to you! Cheers :)