Price search done May 19, 2006 using Froogle, Nextag and other price search systems.
Tools.  Reviews: http://reviews.cnet.com/  ; http://www.brighthand.com

Extras

$25.88, Fellowes PDA Keyboard And Case For Palm M500/M505/M515

$26.25, WriteRight™ Handheld PDA Screen Overlays Clear, micro-thin screen overlays for PDAs help prevent scratches, reduce glare and improve handwriting recognition. Textured surface and low-tack adhesive allow for easy, safe removal. Supports all Palm™ computing platforms and major Windows® CE™ devices. 12 overlays per pack. Compatible with Palm™ III and Handspring, http://store.splitsecondofficesupply.com/fel98024.html

Monochrome (black and white) PDAs

• RIM BlackBerry R857D-2-5 Wireless Handheld/Pager/PDA Device, RIM-857pad$17.99, 10 for $170.00 http://www.store.yahoo.com/glob2000/blrim857pdpa.html
  
• $24.99, Sharp PDA-Style Personal Organizer with 1MB Memory, backlist, from www.BettyMills.com

• $25.50, High-Quality PDA Portable Keyboard (Mini Keyboard) for Palm m500/505 (PKB-150), http://store.yahoo.com/meritline/hipdapokefor.html

• $29.99, Pilot M105 Handheld PDA (With 8mb Memory) Part name: Pilot M105 Handheld PDA (With 8mb Memory), Site id: 118586, SKU: M105. Etech4sale.com, 233 seller ratings

• $38.00, palmOne IIIe Handheld Palm OS - Palm Expansion Rating: 4/5 stars (26 user ratings), Gizmos2go
• $39, palmOne VII Handheld Palm OS - cell phone wireless plans, Palm Expansion Rating: 4/5 stars (4 user ratings) Gizmos2go 
  
• $45.00, palmOne v handheld organizer, Palm OS - Palm Expansion, Rating: 5/5 stars (2 user ratings), Gizmos2go
• $35 ( was $48 in May) Palm IIIx *D *R (3C80301U), , Gizmos2Go SKU: 1701SL, Palm IIIx 4MB Handheld PDA. *D *R (3C80301U), FREE Leather Case (25$ Value!), Refurbished Item , http://www.gizmos2go.com/xcart/home.php?cat=420
• $55.88, palmOne IIIxe Handheld 3C80304U, 8 MB Memory - Palm OS - Palm Expansion, Rating: 4/5 stars (42 user ratings) Gizmos2go
• $73, Palm M125 16MB Handheld PDA *D (P80703U) Expand your horizons and organize your busy schedule with the Palm m125 handheld. With 8 MB of memory, a USB HotSync cradle, and a new expansion card slot, the curvy, sleek Palm m125 offers lots of computing power and versatility. You'll be able to add more powerful applications and store thousands of memos, appointments, addresses, and to-do items. Gizmos2go

Color PDAs

The PDAs systems under $100 with color display use the Palm OS.  There are also a  number of other  Palm PDA  models. The two commonly available across the Internet sales sites are the Zire 31 and Z22.

Palm Zire 31

• runs Palm OS 5.2.8
• $80, http://www.overstock.com/cgi-bin/d2.cgi?PAGE=PRODUCT&PROD_ID=726249&cid=25608&fp=F; no phone
  
• $77, http://gizmos2go.com/xcart/product.php?productid=4119, sent request via their message system for phone call
  
• $79.05, PalmOne Palm Zire 31 color, Handheld PDA with 16mb, USB, MP3 and Earbud (emailed store about quantity and large order discount, May 20)  http://stores.channeladvisor.com/km-electronics/items/item.aspx?itemid=2989082
• Reviews: http://reviews.cnet.com/Palm_Zire_31/4505-3127_7-30843616-2.html?tag=nav; http://www.mobile-review.com/pda/review/palm-zire-31-en.shtml;
  

Palm Z22

• $95, CDW-G, Contact Jason Guenther, 866-723-3395.
• $89, Palmone Palm(TM) Z22 Handheld, 32 MB Memory - Palm OS - Palm Expansion, Bright Color Screen 32MB* of Memory Lightweight Meet the Palm(r) Z22 organizer. It's so easy to use, you can get started in a few simple steps. Pick it up. It's small and light. Turn it on. There's a bright color screen. more...Part #: 1048NA / PALMZ22 http://www.nextag.com/serv/main/buyer/ProductM.jsp?shipping=Ground&sort=subtotal%2C&units=1&ptitle=80866846
• Reviews: PC Editor's Choice Award, http://www.pcmag.com/article2/0,1895,1869799,00.asp ; http://www.the-gadgeteer.com/review/palm_z22 ; http://www.brighthand.com/default.asp?newsID=2690
• 
  

Other Operating Systems

The company Dell provides handhelds using a different operating system than Palm, called the Pocket PC or the Windows CE system. There are no companies providing color PDAs under $100 using this operating system.

• http://www.dell.com/content/products/category.aspx/handhelds?c=us&cs=19&l=en&s=dhs
• Comparison of several Pocket PCs - http://www.vgapocketpc.com/vga-pocket-pc-comparison.php ;  http://www.gaea.ca/en-us/dept_6.html#Pocket%20PC%20Information 
  
• Comparison between Palm and Pocket systems - http://palmtops.about.com/od/pda101/l/blchart.htm