Looking at the low end landscape for the first time in 15+ years, this is what i've found:
Tesoro is the only one that offers a lifetime warranty (to the original owner) anymore. The Compadre is at ~$152 shipped on ebay right now, brand new. Simple but effective.
http://www.tesoro.com/product/detectors/compadre/
The Garrett Ace 150 has more bells and whistles, and about $152 on ebay, shipped, but not as long a warranty.
http://www.garrett.com/hobby/products/ace150.htm
http://www.kellycodetectors.com/garrett/garrett-ace150.htm
There is also Bounty Hunter which has quite the following, and is perhaps the best known in the sub-$150 category. 5 year warranty. E.g. Bounty Hunter Quick Silver
http://www.detecting.com/products/product.cmdl?c=a7cc4f5a2c3c4020
http://www.kellycodetectors.com/bountyhunter/quick_silver_buy.htm
If I were starting out today, i'd probably pull the trigger on the Garrett or the Bounty Hunter because of more features, but do some research, read the review forums, and see what you like the best. I listed links to Kellyco as it is a good place to browse as well. When you settle on one, google search and see who may have the best deal. e.g. beach audio currently has the quicksilver for $115 shipped, but not with the extra accessories!
All the above assumes land or dry white sand hunting, however, if you want one that works well in wet sand, black sand or the surf, you probably won't find it for under $150.

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Let us know what you get, and how well it works for you.