Since Oracle (ORCL) co-President Charles Phillips said in July that the company could spend $70 billion in acquisitions in the next five years — a statement the company retracted the following day — I’ve been curious to see some insightful speculation on what Oracle would buy. One investor I spoke to believes that Oracle looked at 3Par (PAR), which Hewlett-Packard (HPQ) agreed to buy Thursday for a pricey $2.35 billion. (A 3Par securities filing referenced a “Company A” that kicked its tires, along with Dell (DELL) and a “Company B,” subsequently identified as HP.)

Oracle has been relatively quiet since its gonzo acquisition of Sun Microsystems. But as the consulting firm Software Advice points out in an illuminating article and survey, Oracle has averaged about one multi-billion-dollar purchase a year since 2004. Its survey revealed that readers believe Oracle’s mostly likely buyout candidate is Informatica (INFA), a software company valued at about $3 billion and headed by the former Oracle executive Sohaib Abbasi.

Fifth on Software Advice’s list is Salesforce.com (CRM), which has been rumored as an Oracle acquisition target almost as long as it has existed. Oracle CEO Larry Ellison was an initial investor in Salesforce.com, and CEO Marc Benioff — whom I interviewed recently — once worked at Oracle. Investors seem to think either that Salesforce.com is a buyout candidate or undervalued, or both. Its stock has soared 24% since the company reported earnings on Aug. 19.

One gating factor to a Salesforce.com buyout is and always has been its valuation. At about $15 billion in value, Salesforce.com trades for more than 200 times its $74 million in earnings over the last four quarters and 75 times the $200 million analysts expect it to earn next year.

Of course, at $112 billion in value, Oracle has a big check book. And it likes to write checks.