Not true, you can buy corporate bonds from FIIG with a minimum $10k. You don't have to be a sophisticated investor, though that does open up more opportunities.
The bond yield is dependent on the risk you want to take on: govt and bank bonds are typically low - 1.5 to 3% max. Smaller company bonds, with higher risk of default, can pay up to 9%. The happy and safe median is circa 5%. You will also need to decide whether you want a floating or fixed rate bond or an inflation linked bond. The other choice is the currency of the bond, with bonds in A$, US$, Euros, and British pounds available. If you have a view on 4x movement you might consider a foreign currency bond. I bought some US$ bonds when the aussie was at US$1.02 and am now enjoying 12% returns, but that's just the luck of timing.
Obviously, in a rising interest rate/inflation period, fixed rate bonds will sell below their nominal $100 face value. Inflation linked bonds have an increasing face value, while floating rate bonds will typically be selling at above par.
