I'm a seller to you but I'm also a long time buyer on eBay. In here, I'm talking about eBay purchase and DSR system for all of us buyers to think about. 

You are looking for to buy the item cost you $200 in the retail store, and you are willing to pay $100 for it on eBay.  You find 2 sellers, both are selling exactly the same item in the same conditions.  One set the price for $1 and $99 shipping charge, another set the price for $100 and free shipping. 

Does it make you feel different?   Which one do you think a better deal?  Would you give bad DSR rating to the first seller and excellent ranting on the later one?  You still pay total $100 and there is no difference.

You found the item on ebay and the seller offer you a express shipping at $16.50, which is the actual cost without any markups.  Seller did not ship the item for next 2 days, and you received it on the 3th day after your purchase.  When you received the shipment, you found your item being squished in a thin express mail bag, which cost free to the seller.  

Next seller offer you $6.99 for priority mail, which is the actual cost plus some handling charge.  The seller didn't ship for next 2 days but provide you with the tracking number for this shipment and you received it on the 5th day after your purchase.  This seller used a paper wrap and stuffed your item in the a thin poly bag but your item came OK.  

Next seller offer you $5.00 for 1st class mail, which is the actual cost plus some handling charge. The seller shipped on the same day of your payment and used the bubble wrap and other extra shipping materials to protect your purchase. The seller provided you with the tracking number and you received it on the 6th day after your purchase. 

Next seller offer you $3.04 for 1st class mail, which is the actual cost without any markups.  The seller didn't ship for next 2 days and stuffed your item in the a brown paper envelope and it got a hole when it arrived.  You did not get the tracking number for this shipment but you receive it on the 8th day after your purchase. 

Which one do you think is the best deal?  Which one do you give your best DSR ratings?

This only matters to eBay's commission earnings, if it did not matter to buyers.  That's why eBay has created DSR rating system and encourage sellers for free shipping.  Further more, eBay hike up their commission rate to sell on eBay and offer discount for sellers with near perfect DSR ratings.

eBay mis-informed buyers as DSR rating 4 is good in the rating scale of 1-5.  Yes, this sounds right.  However, actually DSR rating 4 is not good for eBay sellers, we get panished by eBay.  DSR rating scale is actually 4-5 and 1-3 is not existing.  Starting 11/3/2008, the seller with lower than average 4.3 rating can't sell on eBay anymore.  So what is trully good rating 4 means on eBay?

eBay opt to compete with Amazon.com where offer buyers the pre-set flat rate shipping charge.  At Amazon, shipping charge on 1 BRA is $4.99 by 1st class mail, and at Victoria's Secret, shipping charge on 1BRA by 1st class mail is $6.99 to $10.99 depending on the product price.     

Again, DSR system is all for eBay and not working for rest of us.  eBay is forcing sellers to lower the shipping charge and to hike up the item cost at the same time to make up a difference, so eBay can earn more commissions.  Actually eBay has instructed all sellers to add the shortage on the shipping cost onto the item cost.  So, after all Free Shipping is not free to buyers.  Here is the example case, one seller used to start all listings at $0.99 with $6 shipping, now offer $9.99 wtih free shipping to start auction. 

Which one would you like?  Which one sound better to you? eBay said avaerage DSR on Free Shipping is 4.8.  How can anyone give less than 5 for free shipping? 

Do you know shipping to Australia can get faster than shipping to Canada?  Do you know it takes 7 days to UK but takes 25 days to Germany?  If your purchase from Canada takes 12 days to get to you, it may not be at the seller's fault.  It is the speed of Customs process and the system of each country's postal service.  We are approching the holiday season and this only get worse.  Please take this into your consideration when you give your DSR rating.  This is another thing eBay don't inform you.

Lastly, here is a well written guide I found on the board to define the DSR ratings for buyers:

http://reviews.ebay.com/WHAT-DSR-RATING-SHOULD-I-LEAVE-A-SELLER_W0QQugidZ10000000007671961