It's been a week, which means it's time to check the most interesting insider purchases. After reading through numerous filings using insider tracking tool Form 4 Oracle, here are my top five today.

The week's buying

Company

Closing Price 8/19/08

Total Value Purchased

52-Week Change

Caribou Coffee

$2.77

$84,212

(58.4%)

Shutterfly (NASDAQ:SFLY)

$9.72

$140,283

(60.9%)

Harris & Harris (NASDAQ:TINY)

$7.54

$132,914

(31.4%)

Eddie Bauer (NASDAQ:EBHI)

$6.39

$90,410

(16.8%)

China Security & Surveillance (NYSE:CSR)

$15.43

$242,400

(9.2%)

Sources: Fool.com, Yahoo! Finance, Form 4 Oracle, SEC filings.

A tiny titan
What is it with our Motley Fool Rule Breakers selections and insider buying? Since February, four of our picks have been featured in this column, including Vertex Pharmaceuticals (NASDAQ:VRTX) in February and Stratasys (NASDAQ:SSYS) last week. Nanotech venture capitalist Harris & Harris makes the cut this week.

Color me encouraged. Harris & Harris is a key stock in my real-money tech portfolio. It's nice to see that insiders agree with my thesis; 11 of them, including chief financial officer Daniel Wolfe, bought shares on Friday.

We've seen this before. CEO Charles Harris joined insiders in buying in bulk in March. Since November, when shares of Harris & Harris dipped under $10 each, the firm's board members, executives, and VC partners have been accumulating stock. Many of those who have rated Harris & Harris in our 115,000-strong CAPS community are equally bullish:

Metric

Harris & Harris

CAPS stars (5 max)

****

Total ratings

709

Bullish ratings

667

Percent Bulls

94.1%

Bearish ratings

42

Percent Bears

5.9%

Bullish pitches

122

Bearish pitches

16

Data current as of Aug. 19, 2008.

It's the very long-term possibilities for nanotech that thrill them. "[Harris & Harris] is finally cheap enough to buy for a long long long term buy. Buy some, hide the shares in a shoebox, come back in 20 years," wrote CAPS All-Star AJL203PSU in a pitch from last month.

Good idea. IBM (NYSE:IBM) just announced successful tests of a 22-nanometer chip manufacturing process. The problem? Big Blue and its chip making peers are teetering on the brink of physical limits; limits that can only be breached with nanotech breakthroughs. That's a rich opportunity for Harris & Harris and its portfolio of companies. It's also just one example of how this stock is a potential multibagger in the making. I'm content to wait for the payoff.

The fair value of China Security & Surveillance
Management won't often tell you what they think their stock is worth. Unless, that is, you're talking about the management of China Security & Surveillance.

CEO Guoshen Tu in March filed a 10b5-1 trading plan to programmatically buy shares between April and September via his investment company, Whitehorse Technology. Notice the terms as described in a company press release:

Under this written plan, Whitehorse intends to purchase up to US$4.8 million worth of the Company's common stock. These purchases will take place weekly over a five-month period beginning April 2008 and will be subject to a maximum price limit of $30 per share. [Emphasis added.]

Can it be any clearer? CEO Tu thinks that China Security & Surveillance is a bargain all the way up to $30 per share, nearly a double from current levels. No wonder he's buying.

There's your update. See you back here next week when we dig through more insider filings in search of the next home run stock.

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