The power over eSATA feature requires support at the PC end as well as the case. If you don't have a powered eSATA port, then it simply won't work.
Judging by the photo of the cable, however, it looks like you can use a regular eSATA port and parasite the power from a USB connection (the common solution on 2.5" eSATA cases).
I've used a variety of external cases, and they are all pretty much the same. The eSATA cases for 2.5" disks that I've used most run around $35, made by Ritmo or Welland. I haven't come across Shentek before, but there are more than a few companies I've never heard of.
If the case is too cheap the interface board inside may be shoddily made, and probably has cheap connectors, so it may break easily. The drive is usually not damaged when the case fails, and you can often just transfer it to another case, although there's a risk you could corrupt the data - that's the biggest worry. It might be worth an extra few dollars to reduce that risk, don't you think?
**I bought my dad an eSATA adapter for his laptop. We discovered that it was no faster for his usage of transferring pictures as the pictures being transferred were slower due to their file size than the 32MB/second maximum speed of the USB hard drive. This was a limitation of the hard drive's speed. 3.5" drives are faster than 2.5" drives.
The problem is i'm located in India and not there is no esata enclosure available here. If I buy on ebay, only few sellers ship to India with appropriate shipping charges. So I'm left with very few options.
@CompulsiveBuilder - If the enclosure fails in case of cheap enclosures, will the already data stored on the disk be affected or the one which is being transferred at the time of failure?