Items and feats that give bonuses to attacks with spells?

[allpossibledogs]

Currently in a Pathfinder campaign, we've just leveled up to 13th and have some downtime. I'm playing a (lightly homebrewed) Sorcerer and while I'm overall quite effective, hitting with spells that require attack rolls is an issue that comes up often. Besides just boosting my Dex (already at 16, about to upgrade to 18), what items, feats and other options are there that can help me with this?
3rd party and homebrew content is accepted, as are custom magic items based on existing spells (already made a couple with a previous character who's now an NPC).

[RNightstalker]

You can do weapon focus and specializations with things like ray spells, and there's an Ioun Stone that gives a competence bonus to attack and a bunch of other things for 30k. Also don't forget that there are a bunch of spells that only require touch attacks, you may want to lean on those as well. Anything that produces a haste effect per the spell gives an unnamed +1 bonus on attack rolls. The Spellwarp Sniper (Complete Scoundrel) let's you warp some area spells into rays that require touch attacks.

[Psyren]

Are you using attack rolls or touch attack rolls? Because the former are going to be very hard to land with a sorcerer's poor BAB. You should focus on going for touch AC instead, which most attack roll spells target.

[Firebug]

Mage's Crossbow (https://aonprd.com/MagicWeaponsDisplay.aspx?ItemName=Mage%27s%20Cross bow) for +2 enhancement bonus for 18k. And then cast Rags to Riches (https://aonprd.com/SpellDisplay.aspx?ItemName=Rags%20to%20Riches) to increase the Enhancement bonus to +3.
Pale Green Prism (https://aonprd.com/MagicWondrousDisplay.aspx?FinalName=Ioun%20Stone%2 0Pale%20Green%20Prism) ioun stone: cracked = +1 competence for 4k and flawed = +1 morale for 28k though casting Heroism is probably better for the Morale bonus.
Haste of course for the +1 untyped bonus to attack rolls.
Cloak of Good Fortune (https://aonprd.com/MagicWondrousDisplay.aspx?FinalName=Cloak%20of%20G ood%20Fortune) for a +1 luck bonus to attack rolls for 12.5k. Or the Bit of Luck (https://aonprd.com/SpellDisplay.aspx?ItemName=Bit%20of%20Luck) spell to add a couple uses (cl/2) to add 1d8 to a failed attack roll in 10 min/level.
Arrowmaster Bracers (https://aonprd.com/MagicWondrousDisplay.aspx?FinalName=Arrowmaster%27 s%20Bracers) for a +20 insight 1/day for 13.9k.

All told: Mage's Crossbow + Cracked Ioun Stone + Heroism + Bit of Luck + Rags to Riches = 24k gp (& 3 spells that last 10 min/level) for +5 to hit with 6 uses of +1d8 on top of that.

You could always cast Reduce Person for an effective +2 to hit (1 size, 1 from increased Dex).

Being Invisible is a +2 bonus to attack, and you target Flatfooted AC. Flatfooted Touch AC is only going to have a few bonuses(notably Deflection) so won't get much higher than 15.

Feat heavy but you can go with Improved Feint(and combat expertise) and Ranged Feint(and probably quickdraw) to throw(say a dagger) as a non-attack feint attempt as a move action and then just use your standard action to target Flatfooted Touch.

[Arkain]

An interesting question may be what kind of spells we are even talking about, as you should be able to land touch attacks of any kind regularly at this point, so I'm suspecting it's not that. If it's about ranged (touch) attacks in particular, a lot of regular archery feats can be used to mitigate penalties, such as Precise Shot to no longer suffer from a -4 for shooting into melee. There's also (Greater) Heroism or the humble Bless for morale bonuses to attack. Lower levels (thus cheap access via Page of Spell Knowledge) offer at least Tactical Acumen to aid the caster and party (though mostly in melee, I guess) and Marid's Mastery if you can arrange for some water. Low bonus weapon ehancements include courageous for a slight increase for morale bonuses and spell storing for full use of a weapon's enhancement bonus.