| Azothath |
Medium sized Mounts
In melee you'll need Ride +7 or so to hit DC 10 for mount AND rider attacks, otherwise only mount attacks OR rider attacks. Assume war trained(WT) as mounts don't work well without it, Price=1.5*(Animal Price).
Mounts are purchased and static whereas Animal Companions are a Class feature and scale with level.
List is from RAW Mounts and Pets
Barding
Size Mount: Cost, Weight, Hit Points based on sz:Med hmnd armr of same type.
Tiny: ×0.5*, ×0.25*, ×0.25.
Sml: ×1*, ×0.5*, ×0.5.
Med: ×2*, ×1*, ×1.
Lrg: ×4*, ×2*, ×2.
Huge: ×8*, ×4*, ×2.
Without Lgt/Med/Hvy Armor Proficiency mounts suffer. Nonproficient with Armor Worn: A character who wears armor and/or uses a shield with which he is not proficient takes the armor’s (and/or shield’s) armor check penalty on attack rolls as well as on all Dexterity- and Strength-based ability and skill checks. The penalty for nonproficiency with armor stacks with the penalty for shields. It's best to get the ArmrChk down to 0.
Animal Feed
Lrg Carnivore 0.1gp/d, 5 lbs.
Lrg Herbivore 0.05gp/d, 10 lbs
Mounts
> Boar CR 2 N Med Anml Sns:low-lgt scent, AC:14, HP:18, Svs:+6 +3 +1, Spd:40, Gore +4(1d8+1){primary} Rch:5. Saddle (Pack $5, Riding $10, Military $20). $150.
> Constrictor Snake CR 2 N Med Anml Sns:scent, AC:15, HP:19, Svs:+4 +6 +2, Spd:20, Climb:20, Swim:20, bite +5(1d4+4 plus grab){primary} Rch:5, SA:constrict(1d4+4). Exotic saddle (Pack $15, Riding $30, Military $60), few Magic Item Body Slots(MIBS). $90+45{WT}.
> Dolphin CR 0.5 N Med Anml Sns:Blindsgt 120(!) low-lgt, AC:13, HP:11, Svs:+4 +5 +1, Swim:80 (!), Slam +3(1d4+1){primary} Rch:5, SQ:hold breath. Exotic Saddle. Few MIBS. $105+52.5{WT}.
> Giant Gecko CR1 N Med Anml Sns:Drkvis 120(!) low-lgt scent, AC:14, HP:11, Svs:+4 +5 +2, Spd:40, Clmb:40, Bite +2(2d4+1){primary} Rch:5, SA:{Spdrclmb}. Saddle. $150.
> Goblin Dog CR1 N Med Anml Sns:low-lgt scent, AC:13, HP:9, Svs:+4 +4 +1, Spd:50, Bite +2(1d6+3 plus allergic reaction){primary} Rch:5, SA:Immune to disease. Allergic Reaction(disease) goblinoid type otherwise Fort12 else -2 Dex -2 Cha for 1 day. Saddle. $50. (cheap)
> Pony Horse CR 0.5 N Med Anml Sns:low-lgt scent, AC:11, HP:13, Svs:+5 +4 +0, Spd:40, war trained 2 hooves +2(1d3+1){primary} else –3(1d3){secondary} Rch:5. Saddle. $45. (cheap and doesn't scare the neighbor's kids)
> Leopard CR2 N Med Anml Sns:low-lgt scent, AC:15, HP:19, Svs:+5 +7 +2, Spd:30, Climb:20, bite +6 (1d6+3 plus grab){primary}, 2 claws +6 (1d3+3){primary} Rch:5, SA:pounce, rake. Saddle. $100+50{WT}.
> Monitor Lizard CR2 N Med Anml Sns:low-lgt scent, AC:15, HP:22, Svs:+8 +5 +2, Spd:30, Swim:30, bite +5(1d8+4 plus grab and poison){primary} Rch:5, SA:Poi Fort14 onset 10r then 1/hr (1d2)Dex cure 1sv. Saddle. $150+75{WT}.
> Ram CR 1 N Med Anml Sns:low-lgt scent, AC:13, HP:11, Svs:+4 +5 +2, Spd:40, Gore +3(1d4+3){primary} Rch:5, SA:Powerful Charge gore (1d8+3). Saddle. $50. (cheap)
> Riding Dog CR 1 N Med Anml Sns:low-lgt scent, AC:13, HP:13, Svs:+5 +5 +1, Spd:40, Bite +3(1d6+3 plus trip){primary} Rch:5. Saddle. $150.
> Wolverine CR 2 N Med Anml Sns:low-lgt scent, AC:14, HP:22, Svs:+5 +5 +2, Spd:30, Burrow:10, Clmb:10, 2 claws +4(1d6+2){prim}, bite +4(1d4+2){prim} Rch:5, SA:Rage. Saddle. $125+62.50{WT}.
Ask your Home GM to expand the list a bit.
After 5th level he might want offer Advanced template. Price will likely triple but WT should not.
Past 7th level he might want to offer Dire creature updates. Price will likely triple-quintuple (based on HD, feats, SA/SQs) and WT will follow with daily Handle Animal checks.