Your best recommendation among these is adding organic matter, in particular compost.
You may want to step back and consider what you want to achieve. Sounds like you planned a garden area with the typical high clay of the Front Range, and need to break up the clay. You said you need material in bulk, so perhaps a 10'x10' garden? I bought a cubic yard of compost for $40/yd plus $50 delivery here in Las Vegas. Mixing amendments into your soil might be a challenge; you certainly will need a rototiller. I also needed a jackhammer for my "soil".
The advantage of compost is it will keep your soil loose for oxygen and moisture penetration plus add nutrient availability. Have been told adding sand and similar to clay produces adobe bricks. Another compost advantage is reducing the impact of your alkaline soil. The CSU Soil Test Lab in Denver will analyze your soil for $40 and give you suggestions.
