As of my last knowledge update in January 2022, I can provide information on some immersion blenders that were popular for soap making and were generally priced under $100. Please note that availability and specific prices may vary, so it's advisable to check for updated models and prices at your preferred retailer.

When selecting an immersion blender for soap making, there are a few key features to consider:

Power and Speed: Look for a model with sufficient power and variable speed settings to ensure it can effectively mix and blend the ingredients for soap making.

Ease of Cleaning: Since soap-making involves working with various oils and ingredients, a detachable, easy-to-clean blender is beneficial.

Durability: Consider a well-built immersion blender to withstand regular use and handling of various soap-making ingredients.

Here are a few immersion blenders under $100 that were commonly recommended for soap making:

1. Mueller Austria Ultra-Stick 500 Watt 9-Speed Immersion Multi-Purpose Hand Blender

Features: A powerful 500-watt motor with nine-speed settings, stainless steel construction, and detachable components for easy cleaning.

Price: Typically priced under $50, making it a cost-effective option for soap making.

2. KitchenAid KHB2351CU 3-Speed Hand Blender

Features: A reliable brand with a 3-speed hand blender, a removable blending arm, and a stainless steel blade that's great for blending various soap-making ingredients.

Price: Falls within or slightly above the $100 mark, but it's possible to find deals or discounts.

3. Hamilton Beach 59765 Immersion Hand Blender

Features: This model offers a powerful motor, various attachments for different tasks, and a durable design.

Price: Typically priced below $40, making it an affordable choice for those on a budget.

4. BELLA Hand Immersion Blender with Whisk Attachment

Features: A versatile option with a powerful motor and whisk attachment, suitable for soap making and various other culinary tasks.

Price: Usually priced under $30, making it an economical choice for beginners or those on a tight budget.

When shopping for an immersion blender for soap-making, read user reviews, check the product specifications, and ensure the blender's design and power meet your soap-making needs. Always prioritize safety and follow the manufacturer's instructions for use.