As eBay now counts 4.5 stars as negative, before thinking that any aspect is "reasonable" vs. "very reasonable," communicate with the seller.  If you have questions or concerns about the description, read it first, then ask questions.  Most sellers communicate, but don't be unreasonable in your expectation.  If it is a holiday weekend, the office might be closed.  You ask a question late Friday afternoon, don't expect a reply until Tuesday sometime.  The seller probably has lots of email to process.  Shipping time returns to communication.  Stuff happens.  Paypal notifications aren't received through no fault of the seller, and you ask after a week, "where is my stuff?"  Canadian customs hangs up items all the time.  That isn't the seller's fault.  Shipping and handling charges:  Most buyers don't have a clue what it costs to ship two pounds, let alone ten.  If shipping charges are stated, weigh them into your buying decision.  If it is "free shipping," the price has probably been inflated.  Either way, you chose and should reward the seller identically with 5 stars.

The bottomline is the communication the seller provides and willingness to assist in any situation.  Ask BEFORE leaving feedback.  It effects the seller's bottom-line AND ability to sell on this venue.